First record of Pilumnopeus convexus ( Maccagno , 1936 ) ( Crustacea , Decapoda , Pilumnidae ) from the Indian coast Swapnil Gosavi

Pilumnopeus convexus (Maccagno, 1936) (Pilumnidae) is recorded for the first time across the Indian coast. The species has so far been reported from coastal waters of the Red Sea, Pakistan and Persian Gulf. P. convexus can be easily distinguished from closely related species in having transversely hexagonal carapace, acute anterolateral teeth and tip of the male left gonopod curved to form a hook like structure. Possible explanations to the new record are discussed.


NOTES ON GEOGRAPHIC DISTRIBUTION
for the first time in Indian waters and suggests a possible explanation for its occurrence there.

Methods
One male and 2 females of P. convexus were collected from the coast at Kuda village (21°37′33″ N, 072°18′17″ E) (Fig. 1), which is located in Gulf of Khambhat (Bhavnagar District, Gujarat state, India).Specimens were collected by hand picking from a rocky rubble intertidal shore during low tide.Photographs were taken from freshly caught specimens in the laboratory using a Canon 1000D camera with a 18-55 mm lens.Crabs were preserved in 70% alcohol and deposited in the Zoology Museum, Department of Zoology, Faculty of Science, the Maharaja Sayajirao University of Baroda, Vadodara, Gujarat, India with accession number (ZL-AR-CR-100).Terminology used for morphological descriptions follows Ghory et al. (2013): carapace length (CL), measured along the vertical median line of the carapace; carapace width (CW), measured horizontally at the widest point of the carapace; and male first gonopod and male second gonopod (G1 and G2, respectively).Morphometric characters were measured in millimetres using digital caliper to the nearest 0.01 mm.
brown with red spots.Female: Carapace cream with reddish brown patch from mesogastric region to intestinal region.Cheliped outer surface reddish brown, inner surface white, fingers brown.Ambulatory legs brown with red spots.
Habitat.The species occurs on rocky rubble shore line.
Distribution.The distribution range of P. convexus is shown in Fig. 8.

Discussion
Morphological examination of the newly examined specimens of P. convexus corresponds with previous descriptions of the same species by Barnard (1955), Davie (1989), and Ghory et al. (2013).Indeed, the newly collected crabs have hexagonal carapace, bilobed frontal margin, structure of anterolateral teeth, armature of chelipeds and ambulatory legs.However, the newly collected specimens differ from the previous descriptions of P. convexus (Barnard 1955, Davie 1989, Ghory et al. 2013) by the placement of sternite 8 and the morphology of G1.Sternite 8 is not visible in the ventral view of the new specimens, while it is clearly visible in specimens examined by Davie (1989) and Ghory et al. (2013).The G1 of the male specimen examined in the present study has an elongated tip compared to specimens described and figured by Barnard (1955) and Ghory et al. (2013).Such noticeable variations could be related to the difference in the size of specimens (Ghory et al. 2013).
Two explanations can be provided for the geographic distribution of these brachyuran crab species, including P. convexus, in northwestern Indian waters.Firstly, the coastal area of Pakistan and Gujarat state, India have a similar marine habitat including rocky and muddy shores, mangroves, and estuaries (Trivedi and Vachhrajani 2012, Trivedi et al. 2012, Shukla et al. 2013).Secondly, the circular movement of surface current of northern Arabian Sea could mediate the transport of larvae of these brachyurans from Pakistani waters to coastal northwestern India (Shetye 1994).