Indian Journal of Geo-Marine Sciences Vol. 42(5), September 2013, pp. 659-664

Study of Color Morphs of Brachyuran Etisus laevimanus Randall, 1840

Trivedi, J. N. and Vachhrajani, K. D. Marine Biodiversity and Ecology Lab, Department of Zoology, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India [E-mail: [email protected]]

(Received 30 January 2012; revised 13 August 2012)

Present study consists the color polymorphism in brachyuran crab Etisus laevimanus Randall, 1840, which is common species found on the rocky shores of indo-pacific region. Total 83 specimens were collected from four different rocky shore sites of Saurashtra coast. Seven different morphs including orange morph, orange morph with brown dots on carapace, green morph, white morph with brown markings on carapace, yellow morph with brown markings on carapace, orange morph with white stripe on carapace and green morph with black spot on carapace were identified. Yellow morph with brown markings on carapace was the most common morph while green morph with black spot on carapace was rare morph found in the study area. Morphs also show peculiar micro habitat preference.

[Keywords: Brachyuran crab, Polymorphism, Etisus laevimanus, Saurashtra coast]

Introduction changes8,9. In invertebrate taxa, and fishes Polymorphism in coloration is known as are studied for polymorphism in colors10. Lee has polychromatism which commonly occurs in different described the biochemical, cellular and ecological taxa. Geographical variation in distribution of bases of color changes in isopod species Idothea and hence difference in coloration is one of montereyensis11,12. Gambel & Keeble have worked the reasons for occurrence of polychromatism1 .Color extensively on the chromatophores and coloration of morphs can be observed in the different age groups shrimp Hippolyte varians13, However brachyuran crab and sexes of the same species and it is thought to be fauna have not been studied thoroughly for having direct impact on mate selection, species polychromatism, except the work of Sangthong & recognition and micro habitat utilization2,3,4. Huyghe Jondeung, who have identified three color morphs of et al.5 carried out a comparative study of ecology Scylla14. During the crab diversity survey of and behaviour on three morphs of a lizard species Saurashtra coast, we came across the presence of Podarcis melisellensis and they found that different morphs of Etisus laevimanus, though polychromatism plays an important role in mate researchers have seen the presence of different selection. Baur6 has identified five different morphs in morphs in the species but the detail description two species of shrimp Heptacarpus pictus and about the morphs is not available. So to fulfill H. paludicola. To study the influencing factors the lacuna the details of different morphs of for coloration changes, one has to describe the Etisus laevimanus are presented in the paper. morphological basis of variation in naturally occurring color patterns of the species. In the fish Materials and Methods Holacanthus ciliaris, habitat preference and breeding The intertidal area of Saurashtra coast is mostly specificity are shown to be responsible for color rocky and provides unique habitat for diverse changes7. It has been reported that if the color changes intertidal flora and fauna. Four different rocky shores are present for short time period like in different age of Sutrapada (Coordinates 20° 49’ 53" N, 70° 29’ 17” group and social displays of the species, ontogeny is E and 20° 50’ 22" N, 70° 28’ 28” E) and Dhamlej the prime reason for color change while genetic (Coordinates 20° 46’ 29" N, 70° 36’ 19” E and 20° 46’ differences and geographic isolation in species 11" N, 70° 37’ 07” E) of Saurashtra coast were population are main reasons for permanent color selected for the study. Belt transect method15 was 660 INDIAN J. MAR. SCI., VOL. 42, NO. 5, SEPTEMBER 2013

adopted for the survey in which 40 × 10 m transects morph, white morph with brown markings on were laid in different zones of rocky shore. Transect carapace, Yellow morph with brown markings on area was searched thoroughly for the presence of the carapace, orange morph with white stripe on carapace, species and on the sighting of the animal, it was hand green morph with black spot on carapace. picked and its microhabitat description was recorded. Etisus laevimamus Randall, 1840 Specimen were brought to the lab and preserved in The species belongs to family: Xanthidae18, 10% formalin. Specimen were identified and subfamily: Estinae19, genus: Etisus20, species: described to the species level following the illustrative 21 16,17 laevimanus . Carapace of the species is distinctly key . The following observations were recorded in broad than long. Amongst all regions, gastric region the laboratory: sex of the specimen, morph type, is fairly demarcated; the branchio-hepatic region carapace length, carapace width, frontal border length, contains three lobes; the antero-lateral margin of the left chelae length and height, and right chelae length carapace has four teeth which are not separated by and height. Different morphs were photographed by small intercalated tooth; the outer margins of the teeth digital camera (Olympus Fe-330) and morphometry are smooth but sometimes they can be endowed with were done by digital vernier calipers. the spinules or denticles; the front is divided into two lobes by single groove in the middle; the anterior Results and Discussion border of the front makes bow like structure; blunt Total 83 specimens were collected, 49 specimens tooth is present on the inner angle of the orbit were male and 24 specimens were female. Total seven (Fig. 1a). Chelipeds are very long and slightly morphs have been identified including orange morph, unequal; in males the chelipeds almost reach the orange morph with brown dots on carapace, green maximum length of the carapace but in females they

Fig. 1—Etisus laevimamus Randall, 1840 (a) Carapace; (b) Cheliped; (c) Female abdomen; (d) Male abdomen; (e) Male pleopod 1 (f) male pleopod 1 (superior part). TRIVEDI AND VACHHRAJANI: COLOR MORPHS OF ETISUS LAEVIMANUS 661

are slightly smaller; carpus has blunt spine at the inner density of brown dots is high on upper margin; the angle; both the surfaces of the chelipeds are smooth inner margin of chelipeds is light brown in color; the but sometimes the outer surface of the cheliped can be fingers are dark brown in color. ornamented with the dots or irregular markings of brown color; fingers are black or brown in color; Orange morph with brown dots on carapace black or brown color of pollex covers some distal part Material: 8 males and 4 females; Measurements: of palm; few cutting teeth are also present on the carapace length- 6.25 cm; carapace width- 3.98 cm; inner side of pollex; the tips of the finger make hoof frontal border length- 1.27 cm; left chelae length- 9.6 cm like structure (Fig. 1b). Ambulatory legs are covered & height- 2.6 cm; right chelae length- 8.3 cm & with hair on both sides; the density and length of hair height- 2.1 cm; Habitat: Rock crevices, tide pool is slightly high on merus as compared to other (Fig. 2b). segments; the dactylus has small hook like spine on Surface of the carapace is smooth and all the the distal end. Outer border of female abdomen is regions are sparsely covered with the brown dots; the covered with small hair (Fig. 1c) while in male density of brown dots is high at frontal and orbital abdomen hair are not present (Fig. 1d); male pleopods region while low at intestinal region; the size of the are slender in shape while the superior margin of brown dots is large in gastric and branchial region; pleopod 1 of male contains small hair tuft on outer very small dots are also present on frontal region as margin (Fig. 1e, 1f); The color of the body ranges well as on antero-lateral border; the frontal border is from yellow to green. dark brown in color and the supra orbital region is covered by small brown dots; the merus and palp of The species has wide spread distribution in rd indo-pacific oceanic region. In Indian subcontinent the 3 maxillipeds are dark brown in color while rest the species is recorded from rocky shores of Gujarat22, of the parts are light orange. Chelipeds are slightly Mumbai state23, Laccadive Islands23, Andaman unequal in size; the outer margins of the merus and Islands23, and Karachi23. Species prefers rocky shore carpus are orange in color with large brown dots; the habitat and is abundantly found in coral reefs. In density and size of brown dots is high on dactylus as current study, the species was recorded in different compared to merus and the inner border of both is kinds of micro habitats like tide pool completely light orange in color; the outer and inner borders of covered by Zoanthus sp., algal assemblage or sand palm are dark brown in color with small brown and filled tide pools having sparse vegetation and in the white dots; the inner margin of pollex and dactylus of rock srevices. large chelipeds contain two and one blunt teeth respectively; straight line of microscopic pits is also Orange morph present on outer margin of dactylus of both fingers; Material: 3 males and 2 females; Measurements: The upper border of merus of walking legs contains carapace length- 4.9 cm; carapace width- 3.25 cm; large and thick hair. frontal border length- 1.1 cm; left chelae length- 8.1 cm & height- 2.6 cm; right chelae length- 7.5 cm Green morph & height- 2.4 cm; Habitat: Rock crevices, tide pool Material: 12 males and 9 females; Measurements: ; (Fig. 2a). carapace length- 3.8 cm; carapace width- 2.9 cm; Surface of the carapace is smooth; gastric, cardiac, frontal border length- 0.7 cm; left chelae length- 6.25 cm hepatic and major part of branchial region is covered & height- 1.9 cm; right chelae length- 5.45 cm & by dark orange color; intestinal region and the area of height- 1.7 cm; Habitat: Sand filled tide pools, algal branchial region adjacent to intestinal region is light assemblage (Fig. 2c). orange in color; the orbital region is light orange in Surface of the carapace is smooth with some color with very small brown dots. Abdominal lobules on hepatic region; the gastric (except segments are covered by light orange color with very urogastric), hepatic and epibranchial region are dark small brown dots. green in color with some scattered white dots while Chelipeds are almost equal; coxa, basis, ischium the cardiac, urogastric, intestinal and mesobranchial and proximal part of merus are light orange in color; regions are covered with very small dots of green major parts of merus, carpus and propodus have dark color; supraorbital region is dark green in color; orange color with brown dots on the outer margin; the merus and palp of the 3rd maxillipeds are dark brown 662 INDIAN J. MAR. SCI., VOL. 42, NO. 5, SEPTEMBER 2013

Fig. 2—Color morphs of Etisus laevimanus; (a) Orange morph; (b) Orange morph with brown dots on carapace; (c) Green morph; (d) Yellow morph with brown markings on carapace; (e) White morph with brown markings on carapace; (f & g) Orange morph with white stripe on carapace; (h) Green morph with black spot on carapace. in color while rest of the parts are light orange. markings are large in gastric, cardiac and intestinal Chelipeds are almost equal in size; both the margins region while it is small in antero-lateral and branchial of coxa and eschium are light orange in color; the region; triangular shape of brown color is clearly outer and inner margins of merus are dark green and observed on meso and meta gastric regions; two lobes light orange in color respectively. Both margins of of the frontal region are covered with circular brown carpus and palm are dark green in color with small markings; frontal border is white in color; supra patch of light orange color on inner margin of palm; orbital region and epistome are covered with small fingers are dark black in color with white tiped hoof brown dots; merus and some part of exopods of 3rd like structure of tips; fingers do not show any kind maxillipeds are covered with scattered and small of dentition; dark coloration of pollex is not extended brown dots, while palp and other parts are light on palm. orange. Chelipeds are almost equal in size; coxa, ischium and merus are white in color on both White morph with brown markings on carapace margins; outer margins of dactylus and palm are Material: 3 males and 5 females; Measurements: covered with brown markings; the size of brown carapace length- 2.1 cm; carapace width- 1.9 cm; markings is large on dactylus; inner margins of palm frontal border length- 0.6 cm; left chelae length- 3.0 cm and dactaylus contain white and few brown margins & height- 1.2 cm; right chelae length- 2.8 cm & respectively; fingers are light brown in color with height- 1.28 cm; Habitat: Crevices of rocks, sand hoof like structure on the tips; two blunt teeth are filled tide pool (Fig. 2d). present on pollex and dactylus, teeth of pollex are Surface of the carapace is smooth and lobulated; all compact while space is observed between teeth of the regions of carapace are covered with unusual dactylus. Except dactylus of walking legs, outer markings of brown color. Size and density of brown border of all the parts contain brown marking while TRIVEDI AND VACHHRAJANI: COLOR MORPHS OF ETISUS LAEVIMANUS 663

the inner border is white; density and size of hair is 3rd maxillipeds are dark brown in color while rest of less on walking legs. the parts are light orange. Chelipeds are slightly unequal; the outer border of chelipeds is orange in Yellow morph with brown markings on carapace color and inner border is white in color; the upper Material: 21 males and 12 females; Measurements: border of carpus and palm contains microscopic carapace length- 3.2 cm; carapace width- 2.3 cm; granules; fingers are dark brown in color with hoof frontal border length- 0.65 cm; left chelae length- 4.1 cm like tips; the dactylus and pollex of both fingers & height- 1.3 cm; right chelae length- 5.4 cm & contain two and three teeth respectively. Small orange height- 1.8 cm; Habitat: Sandy bottom of rock, algal dots are present on thoracic sternum and abdomen. assemblage. (Fig. 2e). Outer border of all walking legs is dark orange in Carapace is yellow in color with scattered brown color with very small brown dots and hair. markings; the surface of the carapace is rough and highly lobulated, the density of lobules is high in Green morph with black spot on carapace hepatic, epibranchial, mesogastric, protogastric, and Material: 2 males; Measurements: carapace antero-lateral region; frontal region and mesogastric length- 2.2 cm; carapace width- 1.8 cm; frontal region contain two cube shaped lobules each. Lobules border length- 0.4 cm; left chelae length- 3.6 cm & are not present in cardiac, metagastric and intestinal height- 0.8 cm; right chelae length- 3.9 cm & region; supraorbital region and epistome are covered height- 1.1 cm; Habitat: Algal assemblage, sandy by brown dots; 3rd maxillipeds and exopods are also bottom of rock. (Fig. 2h). covered by brown dots chelipeds are slightly unequal; Surface of the carapace is rough, green and covered coxa, ischium and merus are white in color; outer with microscopic orange dots, two large black spots border of carpus and palm of large cheliped is covered are present on the carapace, the first one covers the with large spots and unusual shapes of brown color; in area of mesogastric, protogastric, and metagastric small chelipeds the crapus and palm are covered with regions while in juveniles the first spot also covers unusual shapes of brown color; fingers are dark some part of hepatic region; the second spot covers brown in color and contain two blunt teeth on the area of cardiac and urogastric regions; small dactylus and pollex. Outer border of walking legs is unusual light orange shapes are present on hepatic and yellow in color with brown marking while inner mesobranchial regions; frontal border, antero – lateral border is light cream in color. Thoracic sternum and border, supra orbital region and epistome are dark abdomen are also covered by light brown dots; the green in color; small dots of orange color are present upper parts of thoracic sternum also contain four large on merus and palp of the 3rd maxillipeds while rest of dots of brown color. the parts are white in color. Chelipeds are slightly unequal; the outer and inner border of chelipeds are Orange morph with white stripe on carapace dark green and white in color respectively; very small Material: 2 males and 1 female; Measurements: dots of black color is present on the outer border of carapace length- 2.3 cm; carapace width- 1.7 cm; carpus; pollex and dactylus of finger of large cheliped frontal border length- 0.5 cm; left chelae length- 3.1 cm contain two and three teeth respectively amongst one & height- 0.8 cm; right chelae length- 3.7 cm & teeth of pollex is large in size. The outer border of height- 1.1 cm; Habitat: Algal assemblage, sandy bottom walking legs is light orange in color with very small of tide pool, tide pool with Zoanthus. (Fig. 2f & g). and dense black dots while inner border is light Surface of carapace is smooth and orange in color; orange or pale white in color. two large lobes are present on epibranchial region; the Brachyura is the most diverse and well studied surface of mesobranchial region is covered by group amongst marine fauna but as far as Gujarat microscopic granules; large white stripe is present on coast is concerned it is least studied. Etisus the central part of the carapace, which starts from laevimanus is common rocky shore crab and during frontal region and ends in intestinal region; the central the survey we could identify seven different color part of the stripe covers part of metagastric region morphs of the species on the basis of morphological and whole area of cardiac and urogastric region. characteristics amongst them yellow morph with In juveniles the white stripe is also present in the brown marking on carapace was very common while same region; supra orbital region and epistome are green morph with black dots on carapace was rare. In covered with small brown dots; merus and palp of the the present study it is also recorded that the species 664 INDIAN J. MAR. SCI., VOL. 42, NO. 5, SEPTEMBER 2013

explores different types of micro habitats. Rock 13 Gamble, F. W. & Keeble, F. K., Hippolyte variant: a study crevices and sand filled tide pools were the common incolor change, J. microsc. Sci., 43 (1900) 589-698. habitats preferred by different morphs because it gives 14 Sangthong, P. & Jondeung, A. Classification of Three Crab Morphs in the Genus Scylla using Morphometric Analysis, high level of protection from predators. Green morph Kasetsart J. (Nat. Sci.), 40 (2006) 958-970. and green morph with black dots on the carapace were 15 Anderson, D. R., Jeffery, L. L., Bradford, R. C. & Burnham, abundantly found in algal assemblage because the K. P., Guidelines for Line Transect Sampling of Biological green color of algae creates best camouflaging Populations, Journal of Wildlife Management 43 (1) (1979), background to deceive the predator. So, the biotic and 70-78. abiotic factors which play important role in 16 Sethuramalingam, S. & Khan, A. S., Brachyuran of determination of color morph and habitat preference Parangipettai, (Annamalai University) 1991, pp. 93. need to be studied in detail. 17 Jeyabaskaran, R., khan, A. S. & Ramaiyan, V., Biodiversity project on Gulf of Mannar biosphere reserve, (Centre of

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