SOME MORPHOMETRIC ASPECTS OF MUNIDA RUTLLANTI ZARIQUIEYALVAREZ, 1952 (DECAPODA, ANOMURA, GALATHEIDAE) IN SIGACIK

BAY (SOUTHEASTERN AEGEAN SEA)

BY

CENGIZ KOCAK1), SEMIH LEBLEBICI, OKAN OZAYDIN and TUNCER KATAGAN

Department of Hydrobiology, Faculty of Fisheries, Ege University, TR-35100Bornova-Izmir, Turkey

ABSTRACT

A total of 491 Munida rutllanti specimens was captured between depths of 150 and 380 min Sigacik Bay in the commercial trawl fisheries season of 2006-2007. During this sampling,208 females (42.36%) and 283 males (57.64%) were found. Undamaged female (104) and malespecimens (107) were measured for morphometric features such as total carapace length withrostrum, carapace length, rostrum length, rostrum basis width, anterior carapace width, maximumcarapace width, cheliped length, total length, and wet weight. Length–weight relationship parameterswere calculated as W = 2.1623 TL − 4.018 for males, and W = 2.7417 TL − 5.083 for females,respectively.

RÉSUMÉ

Au total, 491 spécimens de Munida rutllanti ont été capturés à des profondeurs allant de 150 à380 m dans la baie de Sigacik au cours de la saison de pêche commerciale de 2006-2007. Au cours decet échantillonnage, 208 femelles (42,36%) et 283 mâles (57,64%) ont été trouvés. Des spécimensintacts, femelles (104) et mâles (107) ont été mesurés sur les critères morphométriques suivants:longueur totale de la carapace avec rostre, longueur de la carapace, longueur du rostre, largeur dela base du rostre, largeur de la partie antérieure de la carapace, largeur maximale de la carapace,longueur du chélipède, longueur totale et poids humide. Les paramètres de la relation longueur–poids ont été calculés ainsi: W = 2,1623 TL − 4,018 pour les mâles, et W = 2,7417 TL − 5,083pour les femelles, respectivement.

INTRODUCTION

Munida rutllanti Zariquiey Alvarez, 1952 is one of the six species of the genusMunida occurring in the Mediterranean Sea. It is distributed from northwestern

1) e-mail: cengiz.kocak@ege.edu.tr

© Koninklijke Brill NV, Leiden, 2008 Crustaceana 81 (7): 873-881Also available online: www.brill.nl/cr

874 CENGIZ KOCAK ET AL.

Spain to Morocco in southern and south-western parts of the western Mediter-ranean, and in the Aegean Sea (eastern Mediterranean). This species lives onmuddy and shell-sand bottoms between 85 and 450 m depth, sometimes downto 1209 m (d’Udekem d’Acoz, 1999).

M. rutllanti was recorded by Kattoulas & Koukouras (1975), and by Koukouraset al. (1992, 1998) from the Greek Aegean Sea. Earlier records of M. rutllanti inTurkish seas are limited to the Aegean Sea: the species was recorded by Kocataset al. (1988) and Koçak et al. (2001) from the Turkish Aegean and these studieswere reviewed in Kocatas & Katagan (2003). The species was also reported byAtes (2003) from the same region.

According to Koçak & Katagan (2008), M. rutllanti was observed at a depthrange of 200 to 400 m, with an occurrence of 100% in samples from the TurkishAegean Sea. The same authors also indicated that the species, which occurred in83.33% of their benthic samples, was the most common anomuran species on theupper slope (200 to 500 m).

Munida rutllanti, though being a common species, has no commercial valuein the Aegan Sea. In the world, however, commercial applications (both formeat (tails) and as a food source for cultured fish) of related galatheids, suchas Pleuroncodes monodon (H. Milne Edwards, 1837), P. planipes Stimpson,1860, Cervimunida johni Porter, 1903, Munida gregaria (Fabricius, 1793), andM. quadrispina (Benedict, 1902) (see Gromitto & Froglia, 1998; Tapella &Lovrich, 2006) suggest that M. rutllanti also has a potential to become aneconomically important species.

There is no a detailed study yet regarding morphometric aspects of Munidarutllanti in the Aegean Sea, and this study is a first attempt to describe themorphometry of M. rutllanti from the region.

MATERIAL AND METHODS

Samples were collected at depths from 150 to 380 m with a commercially usedbottom trawl (with a 24 mm mesh cover net attached over the codend) at a site inSigacik Bay (38◦05′N 26◦35′E to 37◦59′N 26◦54′E) from September 2006 to April2007 (fig. 1). All samples were preserved on board in 5% formalin. Successively,a total of 491 specimens of Munida rutllanti was sorted out from the benthic inver-tebrate fauna sampled. In the laboratory, sex was determined under a stereomicro-scope, by observing the situation of the gonopores: on the coxa of the third pereio-pod in females or the coxa of the fifth pereiopod in males. In addition, in malesthe first two pairs of pleopods are modified to gonopods, the other three pairs aresmall and flap-like. In females, the first pair is absent and the last three pairs are

MORPHOMETRY OF MUNIDA RUTLLANTI 875

Fig. 1. Map of the study area showing the sampling location (") in the Aegean Sea.

elongate and have long setae for carrying the eggs. Six different body parts of 211undamaged specimens (107 males in the size range of 9.00-13.44 mm CL and 104females of 9.03-12.75 mm CL) were measured (fig. 2). Carapace length (CL), totalcarapace length (TCL), maximum carapace width (MCW), and anterior carapacewidth between the anterolateral spines (ACW) were measured with digital callipersto the nearest 0.01 mm. Rostral basis width (RBW) and rostral length (RL) weremeasured with an ocular micrometer mounted on a stereomicroscope (fig. 2). TL,total length (from the tip of the cheliped to the end of the telson) and ChL, chelipedlength (from the tip of the dactylus to the ventral end of the coxa) were measuredwith digital callipers again. In order to provide linear relationships between bodysize and weight of the specimens, wet mass (not blotted with filter paper) (WW) ofthe specimens was determined using a digital balance with a precision of 0.01 g.

An estimation of W–L relationships was made by adjusting an exponentialcurve to the data (Ricker, 1973, 1975):

W = a × Lb

This equation can also be expressed in its logarithmic form:

log W = log a + b log L

where W is total weight (in g), L total length (mm), a the intercept, and b

the slope. The parameters a and b of the W–L relationship were estimatedby linear regression analysis (least-squares method) on log-transformed data,

876 CENGIZ KOCAK ET AL.

Fig. 2. Measurements made on: A, a carapace of the general shape of the genus Munida Leach[adapted from Tapella & Lovrich, 2006]; B, a cheliped of Munida rutllanti Zariquiey Alvarez, 1952from Sigacik Bay (Turkish Aegean Sea); C, a specimen of Munida rutllanti Zariquiey Alvarez, 1952from Sigacik Bay (Turkish Aegean Sea): TCL, total carapace length; CL, carapace length; ACW,anterior carapace width; MCW, maximum carapace width; RL, rostrum length; RBW, rostrum basis

width; ChL, cheliped length; TL, total length.

and the association degree between variables (W and L) was calculated by thedetermination coefficient (r2).

MORPHOMETRY OF MUNIDA RUTLLANTI 877

RESULTS AND DISCUSSION

The length frequency of 211 Munida rutllanti specimens obtained from SigacikBay is given in fig. 3. Basic statistical values of such length and weight variablesare presented in table I. Total length ranged from 71.73 to 105.38 mm for females,and from 76.29 to 119.15 mm for males, respectively. Overall mean total length ofmales was larger than that of females (t-test, P < 0.05) (fig. 3).

Parameters of weight–length relationships as estimated for both sexes are asfollows:

Males: W = 0.0139 TL2.1633 (r2 = 0.7418; N = 107; SE of slope (b) = 0.127; SE a = 0.123)Females: W = 0.0046 TL2.7417 (r2 = 0.8919; N = 104; SE of slope (b) = 0.093; SE a = 0.087)

The b values indicate that Munida rutllanti shows negative allometric growth inboth sexes (t-test, P < 0.05). The t-test results indicated significant differences(P < 0.05) between the slopes (b) of the length–weight relationship for males andfemales (t-test, t = 17.018 > t0.05,211 = 1.65) (fig. 4).

Eight morphometric characters (as described in Tapella & Lovrich, 2006) andthe parameters of their relation with total length and with each other, were calcu-lated for 211 M. rutllanti specimens between sexes (table II). Strong relationshipswere found between total length (TL) and cheliped length (ChL), total carapacelength (TCL), and carapace length (CL), and also between rostrum length (RL)and rostrum base width (RBW).

Information on the morphology of the Mediterranean Munida species is limited.There are only a few studies from the Mediterranean Sea regarding this subject(Gramitto & Froglia, 1998; Mori et al., 2004; Huguet et al., 2005). Huguet et al.

Fig. 3. Length frequency of Munida rutllanti Zariquiey Alvarez, 1952 specimens from Sigacik Bay(Turkish Aegean Sea).

878 CENGIZ KOCAK ET AL.

TABLE IDescriptive values for morphometric features of Munida rutllanti Zariquiey Alvarez, 1952 in Sigacik

Bay (Turkish Aegean Sea)

Morphometric characters Min. Max. Mean ± SE SD Relative value(mm) (mm) (mm) (% of TL)

Males

Total length (TL) 76.29 119.15 93.69 ± 0.954 9.871 —Weight (W ) 1.12 3.44 1.802 ± 0.0491 0.507 —Total carapace length (TCL) 14.47 21.4 17.60 ± 0.143 1.484 18.79Carapace length (CL) 9.0 13.44 10.74 ± 0.094 0.977 11.46Rostrum length (RL) 5.44 8.13 6.83 ± 0.057 0.593 7.29Rostrum base width (RBW) 0.58 1.01 0.80 ± 0.008 0.081 0.85Anterior carapace width (ACW) 6.56 9.2 7.55 ± 0.065 0.669 8.06Posterior carapace width (PCW) 7.84 11.97 9.43 ± 0.094 0.976 10.07Cheliped length (CL) 53.83 89.89 68.52 ± 0.769 7.955 73.13

Females

Total length (TL) 71.73 105.38 83.32 ± 0.767 7.826 —Weight (W ) 1.04 2.84 1.562 ± 0.435 0.444 —Total carapace length (TCL) 15.14 20.75 17.23 ± 0.141 1.435 20.68Carapace length (CL) 9.03 12.75 10.32 ± 0.087 0.890 12.39Rostrum length (RL) 6.02 8.36 6.89 ± 0.058 0.591 8.27Rostrum base width (RBW) 0.68 1.06 0.81 ± 0.009 0.091 0.97Anterior carapace width (ACW) 6.16 9.34 7.25 ± 0.065 0.663 8.70Posterior carapace width (PCW) 7.45 11.18 8.86 ± 0.083 0.843 10.63Cheliped length (CL) 49.67 76.09 58.03 ± 0.574 5.853 69.65

Fig. 4. Weight–length relationship of Munida rutllanti Zariquiey Alvarez, 1952 in Sigacik Bay(Turkish Aegean Sea).

MORPHOMETRY OF MUNIDA RUTLLANTI 879

TABLE IILength–length relationship parameters of Munida rutllanti Zariquiey Alvarez, 1952 in Sigacik Bay

(Turkish Aegean Sea)

Morphometric characters Males Females

Relationship (Log mm) r2 Formula (mm) r2

Total carapace length (TCL) 0.6832 ∗ TL – 0.1014 0.7184 0.8176 ∗ TL – 0.3342 0.8501Carapace length (CL) 0.7342 ∗ TL – 0.4166 0.7253 0.8634 ∗ TL – 0.6448 0.8799Rostrum length (RL) 0.6111 ∗ TL – 0.3705 0.5207 0.7363 ∗ TL – 0.5761 0.6607Rostrum base width (RBW) 0.6997 ∗ TL – 1.4767 0.4709 0.9409 ∗ TL – 1.8985 0.639Anterior carapace width 0.7106 ∗ TL – 0.5231 0.7169 0.8971 ∗ TL – 0.8632 0.8463

(ACW)Posterior carapace width 0.7664 ∗ TL – 0.537 0.6329 0.8619 ∗ TL – 0.7082 0.7256

(PCW)Cheliped length (CL) 1.0768 ∗ TL – 0.2876 0.9645 1.0471 ∗ TL – 0.2478 0.9646

Total carapace length (TCL) 1.0332 ∗ CL – 0.256 0.9332 1.0139 ∗ CL – 0.24 0.9543Rostrum length (RL) 1.1575 ∗ RBW – 1.0629 0.924 1.2468 ∗ RBW – 1.1364 0.9208Anterior carapace width 1.0591 ∗ PCW + 0.0442 0.852 0.9645 ∗ PCW + 0.1178 0.8641

(ACW)

(2005) indicated that males reach larger sizes than females in M. rutllanti off theCatalan coasts (western Mediterranean). This result agrees with the informationin the present study. Those authors also found the same result for M. intermediaA. Milne-Edwards & Bouvier, 1899, and for M. tenuimana G. O. Sars, 1872 intheir study.

Gramitto & Froglia (1998) studied the biology and growth of Munida interme-dia in the western Pomo pit (Adriatic Sea). Those authors stated that males reach aslightly larger size than females. Maximum carapace length (CL) was measured as25 mm for males and 23 mm for females by those authors. The size of 4 to 25 mmCL in males and 5 to 23 mm in females for M. intermedia in their study, contrastswith males in the size range of 9.00-13.44 mm CL and females in the size range9.03-12.75 mm CL for M. rutllanti in the present study. In the northern TyrrhenianSea, Mori et al. (2004) pointed out that sizes ranged from 9 to 27 mm CL for males,and from 10 to 24 mm CL for females in M. intermedia.

Koçak (1998) recorded 70 specimens of M. rutllanti from Bozcaada, Cape Baba,Gökova Bay, and Hisarönü Bay (Turkish Aegean Sea), which were measured tohave between 11 and 24 mm TCL. Those values are similar to the results of thepresent study.

Weight–length (W /L) and length–length (L/L) relationships have been appliedas a basic use for the assessment of stocks and populations (Ricker, 1968). Inconclusion, this basic information on the W /L and L/L relationships of M. rutllanti

880 CENGIZ KOCAK ET AL.

may potentially be useful for benthic ecologists and other biologists for furtherpopulation studies in the Aegean Sea.

The present study is a first attempt at describing some morphometric aspects,and the weight–length relationship of Munida rutllanti in the Aegean Sea. Furtherstudies on other morphometric aspects of the species in the same area are necessaryto extend our knowledge on this subject.

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HUGUET, C., F. MAYNOU & P. ABELLO, 2005. Small-scale distribution characteristics of Munidaspp. populations (Decapoda: Anomura) off the Catalan coasts (western Mediterranean). Journ.Sea Res., 53: 283-296.

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MORPHOMETRY OF MUNIDA RUTLLANTI 881

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First received 20 November 2007.Final version accepted 21 February 2008.