Taxonomic status and phylogenetic relationships of Boulengerula denhardtiNieden, 1912 (Amphibia, Gymnophiona, Caeciliidae)

Mitt. Mus. Nat.kd. Berl., Zool. Reihe 80 (2004) 1, 41-51 30.04.2004

Taxonomic status and phylogenetic relationships of Boulengerula denhardti Nieden, 1912 (Amphibia, Gymnophiona, Caeciliidae)

Mark Wilkinson ’, Simon P. Loader 2, Hendrik Miiller ‘1 & David J. Gower

With 2 figures and 2 tables

Abstract

The Kenyan caeciliid caecilian Boulengerulu denhardti Nieden 1912 was considered to be a junior synonym of Schistometo- pum (Dermophzs) gregorii (Boulenger, 1894) by Loveridge (1936). This synonymy has been accepted, implicitly or explicitly, by all subsequent workers. Re-examination of the holotype and only known specimen of B. denhardti confirmed Nieden’s (1912) assessment that this form represents a distinctive species of Boulengerulu. We resurrect B. denhardti from the synonymy of Schistornetopurn gregorii, rediagnose the species, redescribe the holotype, and provide an updated key to the species of Boulengerulu. The phylogenetic relationships of the species of Boulengerulu are examined on the basis of morphological data. It is concluded that the available morphological data are insufficient to resolve relationships with any confidence at this time. The caecilian fauna of the Tana River region is briefly discussed.

Zusammenfassung

Boulengerula denhardti (Gymnophiona: Caeciliidae) wurde von Nieden (191 2) anhand eines einzigen Exemplars aus dem Gebiet des Tana Flusses im siidostlichen Kenia beschrieben. Im Zuge seiner eigenen Untersuchungen zur Gymnophionen- fauna des Tana-Deltas iiberfiihrte Loveridge (1936) B. denhurdtii in die Synonymie von Schistornetopum gregorii. Diese Syno- nymisierung erfolgte offensichtlich aufgrund einer Fehlinterpretation der publizierten Beschreibung. Unsere Untersuchung des Holotypus von B. denhardti zeigt, dass es sich hierbei urn eine distinkte, valide Art handelt, welche wir hier neu beschreiben und neu diagnostizieren. Ein neuer Bestimmungsschlussel fur alle bekannten Arten von Boulengerula wird ebenfalls vorge- stellt. Die Verwandtschaftsbeziehungen der einzelnen Boulengerulu-Arten werden neu untersucht, wobei gezeigt wird, dass die bekannten morphologischen Merkmale zu deren Auflosung nicht ausreichen. Die Gymnophionenfauna des Tanagebietes wird kurz diskutiert.

Key words: Caecilian, Africa, Kenya, Herpetofauna, Phylogeny

Introduction

Knowledge of the caeciliid caecilian fauna of East Africa began at the close of the 19th Cen- tury, with Giinther’s 1894 report of a caecilian from Ngatana, Kenya. Boulenger’s (1894) description of Dermophis gregorii, which was based on this specimen, and Tornier’s (1897) description of Boulengerula boulengeri from the Usam- bara Mountains, Tanzania soon followed. Two additional caeciliid species were subsequently described from the region of the Tana River of Kenya, Boulengerula denhardti Nieden 1912 and Bdellophis unicolor Boettger 1913. A hiatus in discovery, partly as a result of the First World

War, was ended by Arthur Loveridge’s efforts toward collecting caecilians during his East Afri- can expeditions for the Museum of Comparative Zoology, Harvard. Loveridge had considerable success in the field, leading to the description of several additional species of Boulengerula and scolecomorphid caecilians (Barbour & Loveridge 1928; Loveridge 1932, 1935). During his expedition to the Tana River, Loveridge collected caecilians from what he interpreted to be the holotype localities of the three species that had been reported from this region, D. gregorii, B. denhardti, and B. unicolor. Loveridge’s material included only a single species of caecilian, and, based on a comparison of his material with pub-

’ Department of Zoology, The Natural History Museum, London SW7 SBD, UK. Institute of Biomedical and Life Sciences, Division of Molecular Genetics, University of Glasgow, Pontecorvo Building,

56 Dumbarton Road, Glasgow G11 6NU, UK.

Address corresuondence to M. Wilkinson, Tel: +44 (0)20 7942 5164, Fax: +44 (0)20 7942 5054, E-mail: [email protected] Institute of Evolutionary and Ecological Sciences, Leiden University, Kaiserstraat 63, 23 11 GP, Leiden, The Netherlands.

Received June 3003, accepted August 2003

42 Wilkinson, M., S. €? Loader, H. Miiller & D. J. Gower, Boulengerula denhardti Nieden, 1912

lished reports for the three named species, Loveridge (1936) concluded that all three names were synonymous, with the oldest name, D. gregorii, having priority. Parker (1941) partitioned African and Neotropical Dermophis, and desig- nated gregorii the type species of the strictly African genus Schistometopum, which is repre- sented in both East and West Africa. He and subsequent workers accepted Loveridge’s view that both B. unicolor and B. denhardti are junior synonyms of S. gregorii.

We recently examined the holotype of Boulen- gerula denhardti and found that, as originally recognised by Nieden, it represents a distinctive species of Boulengerula. Here we review Nie- den’s writings on this overlooked species, and Loveridge’s arguments for synonymy, and we resurrect B. denhardti from the synonymy of S. gregorii. We provide a rediagnosis for the species, a redescription of the holotype, and a revised key to the species of Boulengerula. Nuss- baum & Hinkel (1994) assembled a morphological data matrix and used this to investigate the phylogenetic relationships of the species of Boulengerula. We review their study and expand the phylogenetic analysis to include B. denhardti. We also briefly discuss the caecilian fauna of the Tana River region.

Materials and methods

Measures of the holotype of Boulengerula denhardti were made to the nearest 0.1 mm with dial callipers, except total length and circumference. which were measured to the nearest mm by stretching the specimen along a ruler and by winding string around the specimen and then measuring against a ruler, respectively. Vertebral counts were made from X-radiographs. with numbers of nuchal and postcloacal vertebrae determined using the method of Wilkinson (1989). Measures were made separately by each of the authors to give an indication of measurement error.

Parsimony analyses were conducted using PAUP* (Swof- ford 1998). All analyses used branch and bound searches. Decay indices and bootstrap proportions were determined to assess support for hypothesised phylogenetic relationships. We used the parsimony PTP randomisation test (Faith & Cranston 1991) to test the null hypothesis that the data are indistinguishable from random, phylogenetically uninformative data. To assess the support for the paraphyly of Afrocneci- lia sensu Taylor (1968) and of Boulengerula sensu Nussbaum & Hinkel (1994), we defined and enforced topological constraints to find the best trees in which these groups were monophyletic, and compared the fit of the data to these trees and to the optimal unconstrained trees using the Templeton test (Templeton 1983). Bootstrap and randomisation tests used 1000 replicates. Decay indices were determined through analyses enforcing reverse topological constraints. All tree statistics were calculated without excluding uninformative characters.

Status of Boulengerula denhardti

Nieden’s (1912) brief description of Boulengerula denhardti was presented in a systematic review of all the then known African caecilian species, and is preceded by the following (translated) diagnosis for Boulengerula: “Skin without scales. Eyes hidden under the skull bones. Tentacle globular, protrusible, equally spaced between naris and jaw angle. Teeth in the lower jaw in two rows. Squamosals and parietals in contact.” Tornier’s original diagnosis stated that there is only a single row of teeth in the lower jaw, and this is true of B. boulengeri (Taylor 1968, Nuss- baum & Wilkinson 1989, Nussbaum & Hinkel 1994) and also of B. denhardti (but not of other more recently described Boulengerula). Nieden did not comment on the discrepancy and did not report the numbers of teeth or disposition of tooth rows in either B. boulengeri or B. denhardti, which is suggestive of a simple error. Nieden gave a useful account of variation in B. boulengeri and a diagnosis that emphasised the small known range (125-132) in the number of annuli of this species. He concluded this account with his discussion and naming of B. denhardti, translated here as:

“The little variation in the number of annuli in Boulengerula boulengeri has caused me to place a specimen from the ZMB, which belongs to the same genus, in a separate species, because the number of annuli is 165 at a given length of 215 mm, that is 30more annuli than in the aforementioned [B. b.] species. The specimen was collected in the area of the Tana River in southern British East Africa by Mr. Denhardt. To honour the collector, to whom the museum owes a larger collection of ‘Kriechtiere’ from this area, I name this species Boulengerula denhardti n. sp.

The colour of the unfortunately strongly wrinkled specimen is light yellow-brown.”

Subsequently, Nieden (1913) published a treatment of the then known caecilians of the World in Das Tierreich. In both his 1912 and 1913 papers, he provided comparative diagnoses for Boulengerula and Dermophis that clearly indi- cated two conspicuous differences between them, the presence of scales in Dermophis and the eyes being concealed under bone in Boulen- gerula. Emphasising the first difference, Nieden (1912, 1913), as Peters (1880) before him, employed the presence or absence of scales as the first division in his keys to the genera of African and to all caecilians. Nieden’s (1913) diagnosis

Mitt. Mus. Nat.kd. Berl.. Zool. Reihe 80 (2004) 1 43

for Boulengerula repeats the mistaken view that there are two rows of teeth in the lower jaw, masking another substantial difference between Dermophis and Boulengerula as then conceived. Along with Peters (1880) and Werner (1899), Nieden (1912, 1913) pioneered the distinction between primary and secondary annuli that is now well established and much used in caecilian systematics, but he did not make consistent use of this distinction in his diagnoses, descriptions and keys. He made no explicit mention of the absence of secondary annuli in Boulengerula and their presence in Dermophis, and did not make use of this as a diagnostic character. However, his accounts of Dermophis gregorii are based on that of Boulenger (1894), and repeat Boulenger’s observation that the posteriormost annuli of D. gregorii are close to each other, which indicates the presence of secondary annuli. Boulenger (1894) referred to the annuli in this region as duplicated.

Loveridge (1936) reported collecting D. gregorii from six localities in the region of the Tana River Delta. He commented “The Ngatana specimens are topotypes of gregorii, the Kau and Lai- ni of Boulengerula denhardti, the Peccatoni of Bdellophis unicolor. Peccatoni is only fifty miles from Ngatana. The other localities lie between or a little to the south.” However, as is clear from Nieden’s description, B. denhardti lacks such a specific type locality and is reported only as being from the area of the Tana River. We have checked the catalogue of the ZMB and are unable to find any more specific information on the provenance of the holotype than that provided by Nieden.

Loveridge based his synonymy only upon the information on the number of annuli and colouration of the species provided by Nieden (1912). His material conformed to Boettger’s description of Bdellophis unicolor as “Uniformly glossy black resulting in a lacquered appearance” when freshly caught and “plumbeous, slightly darker above than below” in preservative. Lover- idge (1936: 375) considered Nieden’s description of B. denhardti as “light yellowish brown” and Boulenger’s description of D. gregorii as “Dark brown above, paler beneath’ to be “based on a specimen in various stages of fading.” The holotype of B. denhardti is undoubtedly faded but its paleness suggests little colouration in life, and is characteristic of old specimens of B. changamwensis Loveridge, 1932 and B. boulengeri (pers. obs.). Based on comparisons with other Boulen- gerula we predict B. denhardti to be light blue or

pink in life, with a slightly darker middorsal band, very different from the more uniformly dark colouration of the holotype of D. gregorii.

Loveridge (1936) also compared the total number of primary and secondary annuli, reported as 160 for the holotype of D. gregorii by Boulenger and 165 for the holotype of B. denhardti. The difference is unimpressive but the comparison fails to take into account the fact that the holotype of D. gregorii has both primary and secondary annuli whereas B, denhardti has only primary annuli. Loveridge acknowl- edged the importance of distinguishing between primary and secondary annuli and reported the number of primary annuli in his samples of D. gregorii to range from 107 to 119, but he did not discuss the number of primaries in B. denhardti. The omission is surprising given that Loveridge had great familiarity with Boulengeru- la, having collected and described species from Kenya and Tanzania, all of which lack secondary annuli.

Taylor (1968) confirmed Loveridge’s synonymy of Bdellophis unicolor with D. gregorii by examining the holotype of the former species but reported that he had not seen the holotype of Boulengerula denhardti. We have also examined the holotypes of B. unicolor and D. gregorii and concur with Loveridge (1936) and Taylor (1968) that the former is a junior synonym of the latter. Bauer et al. (1993) listed B. denhardti in their type catalogue of caecilians and salamanders in the Zoological Museum, Berlin as a synonym of Schistometopum gregorii, without stating whether they examined the holotype. Nussbaum & Hin- kel (1994) and Nussbaum & Pfrender (1998) revised the taxonomy of Boulengerula and Schisto- metopum, respectively, but did not examine the holotype of B. denhardti, accepting that Lover- idge had shown this species to be a junior synonym of S. gregorii.

Clearly, Loveridge’s taxonomy was hampered by not having seen the holotype of B. denhardti. His synonymy was made without any discussion of Nieden’s diagnoses of Boulengerula and Der- mophis, and the character differences they implied for B. denhardti and D. gregorii. His case for synonymy was superficial and mistaken. We have verified the reported differences and pro- pose to remove B. denhardti from the synonymy of D. gregorii. Boulengerula denhardti is distinct from all other species of Boulengerula in its number of annuli, and in the disposition of the tongue and teeth, and warrants specific recogni- tion.

44 Wilkinson. M.. S. P. Loader. H. Miiller & D. J. Gower, Boulengerula denhardti Nieden, 1912

Fig. 1. ZMB 22350, the holotype of Boulengerzrla deiilinrdti Nieden. showing general views of the body and detailed views of the head and terminus.

Mitt. Mus. Nat.kd. Berl., Zool. Reihe 80 (2004) 1 45

Table 1 Morphometric and meristic data for ZMB 22350, the holotype of Boulengerula denhardti. Values determined separately by each author give some indication of measurement error.

MW SPL HM DJG

Total length Total annuli Total vertebrae Vertebrae in nuchal region Post-cloaca1 vertebrae Distance between tip of snout and jaw angle Distance between tip of lower jaw and jaw angle Head width at level of jaw angles Head width at anteriormost nuchal collar groove Distance between tip of snout and anteriormost nuchal collar groove,

Length of first nuchal collar, measured laterally Length of second nuchal collar, measured laterally Distance between anterior margin of upper lip and tip of snout Distance between tentacle and naris Distance between tentacles Distance between nares Distance between naris and jaw angle Distance between naris and tip of snout Distance between naris and margin of upper lip Distance between tentacle and jaw angle Distance between tentacle and tip of snout Distance between tentacle and margin of upper lip Width at midbody Width at anterior margin of terminal shield Length of terminal shield, measured laterally Circumference at midbody Circumference 5 annuli anterior to terminal shield Premaxillary-maxillary teeth Vomerine teeth Palatine teeth Dentary teeth

measured laterally

213 161 168

3 4 3.9 3.4 2.9 3.0 5.3

1.8 1.9 1.3

213 161 168 - -

3.8 3.4 2.8 3.0 5.2

1.8 1.9 1.2

2.0 1.9 2.8 2.8 1.5 1.5 3.3 3.3 0.9 0.9 1.0 1.0 1.5 1.4 2.5 2.5 0.4 0.5

3.0 3.1 1.9 2.3

10 11 8 10

19 19 9 9

15 15 19 19

2.9-3.8 3.5

213 -

161 161 168 168

3 3 4 4

3.8 3.8 3.3 3.3 3.1 3.1 3.2 3.1 5.5 5.2

1.7 1.7 1.8 2.0 1.4 1.2 2.0 2.0 2.9 - 1.5 -

3.3 3.2 0.7 0.9 1.0 1.1 1.5 1.4 2.4 2.5 0.4 0.5 2.8-3.8 3.6 3.1 2.9 2.0 2.2

10 11 9 9 - -

Boulengerula denhardti Nieden

Boulengerula denhardti: Nieden 1912, Ubersicht iiber die afrikanischen Schleichenlurche (Amphibia apoda). Sitzungs- berichte der Gesellschaft naturforschender Freunde zu Berlin (1912): 186-214.; Nieden, 1913, Amphibia, Gymno- phiona. Das Tierreich, Lieferung 37, 40 pp.

Dermophis gregorii: Loveridge, 1936, Mem. Mus. Comp. Zool. Harvard, 91 472-473. Taylor 1968, Caecilians of the world: a taxonomic review. University of Kansas Press, Lawrence, i-xiv + 848 pp.; Nussbaum & Pfrender 1998, Revision of the African caecilian genus Schistometopum Parker (Amphibia: Gymnophiona: Caeciliidae). Misc. Publ. Mus. Zool. Univ. Michigan. No. 187: 1-32.

Ho lo type . Museum fur Naturkunde der Hum- boldt-Universitat zu Berlin, ZMB 22350, a specimen of indeterminate sex from the area of the Tana River, Kenya (southern British East Afri- ca). Collected by C. Denhardt.

Referred specimens: Known only from the holotype. D i a g n o s i s. A Boulengerula with a unique com- bination of no splenial teeth and a tongue with a free anterior edge. Differs from all other Boulen- gerula except Boulengerula fischeri Nussbaum & Hinkel, 1994 in having more than 150 annuli and

more than 160 vertebrae. Differs from B. fischeri in having less than 180 annuli and less than 190 vertebrae.

D e s c r i p t i o n of t h e h 010 type. Photographs of the holotype are presented in Fig. 1, and some morphometric and meristic data are given in Ta- ble 1. The specimen is in fairly poor condition. The jaws have been cut, most teeth are missing from the lower jaw, the colour is faded and the body is somewhat stiff and shrivelled. The skin of the left side of the head has been reflected, and there is a midventral incision beginning 67 mm anterior to the body terminus and extending forward 10 mm. The body is strongly and ar- tefactually dorsoventrally compressed throughout, and of relatively uniform width, narrowing only slightly just behind the head and nuchal collars; ratio of length (213 mm) to width at midbody (3.3 mm) about 65.

In dorsal view, the sides of the head converge gently anteriorly to the level of the tentacular apertures, and a little more strongly to the level of the nares. Beyond the nares, the snout tip is bluntly rounded in dorsal and lateral views. In

46 Wilkinson. M., S. P. Loader, H. Muller & D. J. Gower, Boulengerulu denhardti Nieden, 1912

lateral view, the margin of the upper jaw (the upper lip) and the top of the head are fairly straight from the level of the angle of the jaw to about midway between the naris and tentacular aperture. Anterior to this point, the top of the head curves gently ventrally down to the tip of the snout, and the upper lip curves more strongly ventrally to the anterior margin of the mouth, which is the deepest part of the snout, and then curves strongly dorsally up to the snout tip.

The eyes are not visible externally nor with the skin reflected. If present, they are covered by the squamosal. Faint whitish spots are visible at the expected position of the eye, and on the left only, this eyespot extends as a faint stripe to the tentacular aperture. In lateral view, the assumed position of the eye is slightly closer to the lip than to the top of the head. The tentacular apertures are subcircular horseshoe-shaped grooves, surrounding a flap of skin that is unin- terrupted posteriorly. Each tentacular aperture is slightly elevated and very close to the lip (0.5 mm), slightly below an imaginary line between the naris and jaw angle, and closer to it than to the lip. The tentacles are laterally placed, just visible from above and slightly more appar- ent in ventral view, much closer to the assumed position of the eye than to the naris. The left tentacle emerges from beneath the anterior margin of the squamosal into a pit in the maxillopa- latine. The nares are rather inconspicuous, smaller than the tentacular apertures. They are ovate and deeper than wide on the right, and little more than a vertical slit on the left. They are dorsolaterally placed, a little above the apex of the snout in lateral view, faintly visible from above and a little more clearly from below, and closer to the snout tip than to the anterior margin of the mouth. The mouth is recessed with the snout projecting moderately beyond the anterior margin of the mouth and the lower jaw. In ventral view, the mouth is rather squarish and much more blunt than the tip of the snout, with fairly straight, slightly oblique lateral, and transverse anterior margins.

The teeth are pointed, recurved, and decrease in size posteriorly. Premaxillary-maxillary teeth are monocusped and the tooth row is short, extending to about level or just behind the posterior margins of the choanae. Vomerine and palatine teeth are bicusped and separated by large diastemata. Vomerine teeth are larger than palatine teeth and smaller than premaxillary-maxillary teeth. They are in a very short row that does not extend to the anterior limit of the choa-

nae. The palatine series begin at the level of the posterior margins of the choanae and the termi- nation of the premaxillary-maxillary series, and extend posteriorly close to the angles of the jaws. The ridge bearing the vomerine and palatine teeth is not visible in lateral view. Only three dentary tooth crowns are present, these are monocusped and larger than the teeth of the upper jaw. There are no splenial teeth and no splenial ridge on the lower jaw. The premaxillary and vomerine teeth each form a continuous arc with no anteromedial diastemata. The last (posteriormost) two teeth of either side of the palatine series are slightly more medially positioned than adjacent teeth.

The choanal apertures are subcircular, slightly longer than wide and their long axes are slightly oblique. They are separated from each other by a distance that is slightly less than the sum of their individual widths. They are bordered by the vomers medially and anteriorly and by the maxil- lopalatines laterally and posteriorly. Each choanal valve comprises two fleshy flaps bordering a slightly oblique slit. The surface of the tongue is free and slightly pointed anteriorly. It is smooth except for some posteromedial plicae, and it lacks a longitudinal medial groove and narial plugs. It is separated from the gingivae by a deep groove.

The nuchal region is scarcely wider than the adjacent body, and it is creased and distorted on the right side. The two nuchal collars are delim- ited by three nuchal grooves. The first (anteriormost) groove is complete ventrally and laterally, and incomplete middorsally. The second groove is complete and the third nearly so, with a slight midventral gap. Laterally, the nuchal grooves are a little paler than the collars. Transverse grooves are present ventrally and dorsally on the first and second collars, respectively, with that on second collar being shorter than that on the first. A faint midventral longitudinal groove extends posteriorly from a little behind the anterior tip of the chin to cross the ventral transverse groove of the first nuchal collar.

There are 168 vertebrae, of which three are in the nuchal region and four are postcloacal, the latter probably an artefact of shrinkage. The grooves delimiting the 161 primary annuli (not including the terminal shield) are mostly complete throughout the body. They are slightly paler than the background colour of the body, having whitish margins, especially laterally. The posteriormost annular groove is complete dorsally but interrupted by the disc ventrally. Thus,


Table 2. Character states for Boulengerulu denhurdti used in the phylogenetic analysis. Character numbers (N) and character state symbols (S) are those of Nussbaum & Hinkel (1994).

N Character state description S

1 2 3 4 5 6 7 8 9

10 11 12 13

14 15 16

Eye under bone 150 or more primary annuli No secondary annuli Scales absent No splenial teeth Tongue free along lateral and anterior margins Vomerine and palatine teeth separated by a distinct gap Terminal shield Terminal keel Tongue smooth (narial plugs absent) Ratio of total body length: body width between 25 and 60 Mesethmoid covered dorsally by frontal bones Posterior limit of premaxillary-maxillary tooth row ending more than two tooth positions before the palatine series Premaxillary-maxillary teeth monocusped Vomeropalatine teeth bicusped Choanal valves do not near the oDening into the mouth chamber

17 A narrow dorsal band of dark pigment

1 2 1 1 2 0 2 1 1 0 1 0 2

1 0 1 2

the disc does not lie entirely within the relatively short unsegmented terminal shield. The shield is bluntly rounded except for a distinct posteromedial vertical keel. The vent is a little irregular and sub-circular, possibly circular or transverse in life, lying at the centre of a depressed subcircular disc lacking distinctive colouration. The disc has a pair of large anterolateral denticulations, separated by a smaller partly divided anteromedial denticulation. Posteriorly there are five somewhat irregular denticulations. There is no indication of papillae on the disc. The colour of the holotype is a faded, light tan brown, with slightly paler head and mandibles, and a faint indication of a darker middorsal stripe.

Remarks . Nieden’s (1912) report of 165 annuli likely included the two partially subdivided nuchal collars. Because it is known only from the holotype, we have no direct evidence of the range of variation within the species. Generalising from other Boulengerula, the numbers of annuli and vertebrae may be expected to have a range of about 10% of the total numbers, and the diagnosis is for- mulated to accommodate this variation.

Phylogenetic relationships

Taylor (1968) transferred three of the four then recognised species of Boulengerula to a new genus, Afrocaecilia, on the basis of their posses- sing splenial teeth and a free tongue. Nussbaum & Hinkel (1994) argued that these characters are primitive, that they may be correlated rather

than independent (because the presence of splenial teeth precludes the attachment of the tongue), and thus that Afrocaecilia rests upon very unstable foundations. They went on to state that “It is clear from inspection that Afrocaecilia and Boulengerula, as conceived by Taylor (1968), are artificial taxa”, and they performed two cladistic parsimony analyses in order to test this hypothesis.

Nussbaum & Hinkel’s (1994) phylogenetic analysis employed 17 morphological characters, scored for an ingroup comprising the five species of Boulengerula and the South American caeciliid Brasilotyphlus braziliensis (Dunn 1945). The tree was rooted using alternatively a hypothetical ancestor, scored for the inferred primitive condition of each character, or two stegokro- taphic East African caeciliids (Sylvacaecilia grandisonae (Taylor 1970) and Schistometopum gregorii) together with the zygokrotaphic West African (neither East African nor stegokro- taphic, contra Nussbaum & Hinkel 1994) caeciliid Geotrypetes seraphini (DumCril 1859). Multi- state characters were treated as ordered. The ordering was not explicitly justified or explained but is consistent with that which would be pro- duced using the method of intermediates (Wil- kinson 1992). Both analyses yielded a single optimal tree in which Taylor’s Afrocaecilia is paraphyletic with respect to a sister group pair- ing of Boulengerula boulengeri and Brasilo- typhlus braziliensis. Nussbaum & Hinkel’s studies led them to reject Taylor’s generic taxonomy and to place Afrocaecilia in the synonymy of Boulen- gerula.

48 Wilkinson, M., S . P. Loader, H. Miiller & D. J. Gower, Boulengerula denhardti Nieden, 1912

Nussbaum & Hinkel’s (1994) phylogenetic analysis was a laudable attempt to objectively test the monophyly of Afrocaecilia. However, they provided no measures of support for their inferred relationships, no assessment of whether the monophyly of Afrocaecilia could be rejected statistically by their data, and no numerical assessment of the quality of their data. Thus we performed additional phylogenetic analyses of Nussbaum & Hinkel’s data, both as published,

and with the addition of data for Boulengerula denhardti (Table 2) . Nussbaum & Hinkel (1994) included Brasilotyphlus braziliensis in the ingroup and assumed ingroup monophyly based on “overall similarity and the shared derived state of a terminal keel, a specialised character not observed outside of the ingroup.” We are less convinced of any close relationship between Bra- silotyphlus and Boulengerula. Weak terminal keels are present also in caecilians of the ende-

Brasilotyphlus braziliensis

Boulengerula boulengeri

Boulengerula changam wensis *

Boulengerula fischeri*

Boulengerula uluguruensis *

Boulengerula taitanus*

Brasilotyphlus braziliensis

Boulengerula changam wensis

Boulengerula denhardti


Boulengerula fischeri

Boulengerula uluguruensis

Boulengerula ta ifan us

Boulengerula denhardti


Boulengerula changam wensis

Boulengerula fischeri

Boulengerula uluguruensis

Boulenge rula ta itan us

Fig. 2. Inferred phylogenies for Boulengerula. (a) Most parsimonious tree for Nussbaum & Hinkel’s (1994) original data (L = 30; CI = 0.8; RI = 0.857). Ingroup relationships are identical when an hypothetical ancestor is used in place of the caeciliid outgroups (Tree length, L = 26; Consistency Index, CI = 0.846; Retention index, RI = 0.667). (b) Strict component consen- sus of six most parsimonious trees (L = 32, CI = 0.750, RI = 0.826) for Nussbaum & Hinkel’s (1994) data augmented by the inclusion of Boulengerula denhardti. Ingroup relationships are identical when a hypothetical ancestor is used in place of the caeciliid outgroups (L = 28, CI = 0.786. R1 = 0.6). (c) Most parsimonious trees (L = 28, CI = 0.857, RI = 0.895) for Nussbaum & Hinkel’s (1994) data augmented by the inclusion of Boulengerula denhardti and with Brasilotyphlus braziliensis excluded. Ingroup relationships are identical when an hypothetical ancestor is used in place of the caeciliid outgroups (L = 24, CI = 0.917, RI = 0.778). Asterisk indicates species fitting Taylor’s (1968) diagnosis of Afrocaeciliu. Numbers are decay indices (below branches) and bootstrap proportions for analyses using outgroups, followed by bootstrap proportions for analyses using a hypothetical ancestor where this is different (above branches).

Mitt. Mus. Nat.kd. Berl.. Zool. Reihe 80 (2004) 1 49

mic African Scolecomorphidae as well as in some Neotropical caeciliids of the genus Micro- caecilia (pers. obs.) making the presence of a terminal keel a less compelling synapomorphy of Brasilotyphlus and Boulengerula. Hence our ex- panded analyses were performed both with and without Brasilotyphlus.

Our reanalyses reproduced the reported results (Fig. 2a), except for minor differences in reported tree statistics. However, bootstrap proportions were mostly very low, suggesting that the data do not provide much support for, or allow much confidence in, the relationships inferred from the data. Decay values were also low. Only two extra steps are required to overturn each of the clades recovered in the most parsimonious tree (MPT). Using Templeton tests we were unable to reject the null hypotheses of no significant difference in fit between the optimal unconstrained trees, in which Afrocaecilia sensu Taylor (1968) and Boulengerula sensu Nussbaum & Hinkel (1994) are paraphyletic, and suboptimal trees in which these groups were constrained to be monophyletic (P = 0.083-0.366). Finally, the null hypothesis that the data are indistinguishable from random, phylogenetically uninformative data could be rejected only when the three caeciliid outgroup taxa were included in the randomisation (PTP = 0.001). With the hypothetical ancestor, or with the caeciliid outgroups not included in the randomisation, we were unable to reject the null hypothesis (PTP = 0.066 and 0.129 respectively). These results are not very surprising. Only eight (i.e. less than half) of the characters vary in a phylogenetically informative way across the ingroup, and this is insufficient to provide a well supported hypothesis of relationships for the six ingroup taxa. Thus, we contend that the ingroup data provide no basis for compelling inferences of phylogenetic relationships within the ingroup, and that they do not provide strong justification for placing Afrocaecilia in the synonymy of Boulengerulu.

The addition of B. denhardti does not alter this general picture. Analysis yields six MPTs with a poorly resolved strict component consen- sus tree (Fig. 2b). In the six MPTs, B. denhardti is recovered as the sister group of B. fischeri, of B. boulengeri or of B. boulengeri and Brasilo- typhlus braziliensis. Bootstrap proportions are unimpressive and decay indices are minimal. Templeton tests reveal that the shortest trees in which either Boulengerula, or Afrocaecilia excluding B. denhardti, or Afrocaecilia including B. denhardti are monophyletic do not provide a sig-

nificantly worse explanation of the data than the unconstrained trees in which neither Boulengeru- la or Afrocaecilia are monophyletic (P = 0.48, P = 0.48 and P = 0.156-0.48 respectively). Ran- domisation tests do not allow rejection of the null hypothesis that the data are indistinguishable from random when the caeciliid outgroups are included but not randomly permuted (PTP = 0.246) or when the hypothetical ancestor is used (PTP = 0.198).

With Brasilotyphlus braziliensis excluded, there are three MPTs in which B. denhardti is the sister species of B. boulengeri (Fig. 2c), without any im- provement in decay analyses or bootstrap proportions. Templeton tests reveal that the shortest trees in which Afrocuecilia is monophyletic (with or without B. denhardti) do not have a signifi- cantly worse fit to the data than the most parsimonious trees (P = 0.180 and 0.157 respectively). As when Brasilotyphlus braziliensis is included, randomisation tests do not allow rejection of the null hypothesis that the data are no better than random, phylogenetically uninformative data when the caeciliid outgroups are included but not randomly permuted (PTP= 0.118) or when the hypothetical ancestor is used (PTP = 0.063), though the latter value is nearly significant.

B. denhardti appears to be most closely related to either B. fischeri or B. boulengeri but our analyses suggest that the available data are simply insufficient to allow robust conclusions regarding the relationships among any species of Boulen- gerula at this time. In contrast to their treatment of Boulengerula and Afrocaecilia, Nussbaum & Hinkel (1994: 754) were more circumspect in drawing taxonomic conclusions regarding Bou- lengerula and Brasilotyphlus, despite their analyses indicating paraphyly of the former with respect to the latter. They noted that “Knowledge of relationships is insufficient, however, to fully justify conclusions concerning the relationships of B. braziliensis, and no taxonomic action is re- commended.” In our opinion, Nussbaum & Hin- kel’s (1994) synonymy of Afiocaecilia and Bou- lengerula was premature given the limitations of the available data for testing their view that neither genus was natural. This is not to say that additional data would not provide a stronger basis for this synonymy, only that in the absence of such data taxonomic actions are necessarily more speculative and risky. We recommend no further taxonomic action in the absence of additional data that provide a clearer picture of both the composition of the ingroup and relationships within it.

50 Wilkinson, M., S. €? Loader, H. Miiller & D. J . Gower, Boulengerula denhardti Nieden, 1912

Key to Species of Boulengerula

1. More than 150 primary annuli . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - Fewerthen150 primary annuli . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. No splenial teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Boulengerula denhardti - Splenial teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Boulengerula jkcheri 3. Splenial teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - No splenial teeth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. Fleshy pink in life (uniform tan if faded in preservative) . . - Bicolored with darker dorsum.. . . . . . . . . . . . . . . . . . . . . . . . 5. Strong diastemata between vomerine and palatine teeth . . - Diastemata weak or absent . . . . . . . . . . . . . . . . . . . . . . . . . . .

Discussion

Boulengerula denhardti is very different and in- stantly distinguishable from Schistometopum gregorii based on obvious features, including several external morphological traits that are readily determined without the aid of magnification. Most of these features are implied by Nieden’s generic diagnoses and species accounts. Unlike the latter species, B. denhardti has an unsegmented body terminus, a terminal keel, no secondary annuli, no scales, no splenial teeth, and the eye is concealed under bone. That B. denhardti was syno- nymised with S. gregorii, and that it languished in synonymy for nearly seventy years despite several revisionary works addressing the systematics of Boulengerula and Schistometopurn, underlines the desirability, as far as is practical, of examining all relevant type material before proposing or endorsing proposed synonymies.

With the exception of B. changamwensis, most Boulengerula species are known from montane regions. The ressurection of B. denhardti, adds a fourth species to the known caecilian fauna of Kenya, extends the distribution of this genus northward by about one degree of latitude and of longitude, and provides further indication that the genus, as currently conceived, occupy May, both montane areas and coastal plains. The geo- graphically closest congeneric species are B. changamwensis from near Mombassa and B. taitanus Loveridge, 1935 from the Taita Hills. In describing B. changarnwensis, Loveridge (1932) suggested it might be intermediate between B. uluguruensis Barbour & Loveridge, 1928 and B. denhardti. Such a relationship is pos- sible, but without much more detailed study the phylogenetic relationships within Boulengerula must be considered unresolved.

The caecilian fauna of the Tana River region of Kenya is poorly known, with no collections of caecilians having been reported from since Loveridge’s 1933-4 expedition. Nussbaum & Pfrender (1998) stated that no serious attempt

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Boulengerula boulengeri

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Boulengerula taitanus

. . . . . . . . . . . . . . . . . . . . . . . . . . . Boulengerula changamwensis

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Boulengerula uluguruensis

had been made to collect caecilians from this region, but one of us (MW) searched briefly (about five hours of digging) and unsuccessfully for caecilians in the vicinity of Lake Kenyata (previously Lake Peccatoni) in December, 1995. The region is very fertile, with extensive agriculture. It has been resettled with considerable dis- placement of the native tribes that assisted Loveridge in collecting S. gregorii, and patterns of land use are probably considerably changed also. MW’s discussions with local people, many of whom are engaged in subsistence agriculture, failed to determine whether caecilians still occur in this region. Further fieldwork should be direc- ted toward the Tana River region to establish the extent of its caecilian fauna. The conserva- tion status of both S. gregorii and B. denhardti in this region might be considered of concern, but in the absence of concerted efforts to recollect these species they must be considered ‘data defi- cient’ at this time.

Acknowledgements

We thank Rainer Gunther and Detlev Langer for access to specimens in their care and for their hospitality in Berlin. We thank Gunther Kohler for loaning the holotype of Bdellophis unicolor. Phil Hurst (NHM) took the photographs. HM is funded by a NHM Department of Zoology studentship, and SPL by a NERC studentship (NER/S/A/2000/03366), Fund- ing for MW, SPL and DJG to travel to Berlin was provided by the NHM. MW’s fieldwork in Kenya was supported by NERC GST/02/832.

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Documents

Taxonomic status and phylogenetic relationships of Boulengerula denhardtiNieden, 1912 (Amphibia, Gymnophiona, Caeciliidae)