INDICA, A NEW SPECIES OF MOLE CRAB (, , ) FROM THE SOUTH WEST COAST OF INDIA

BY

JANET HAIG Allan Hancock Foundation, University of Southern California, Los Angeles, California 90089, U.S.A. T. MURUGAN and N. BALAKRISHNAN NAIR Department of Aquatic Biology and Fisheries, University of Kerala, Beach (P.O.), Trivandrum 695007, Kerala, India

INTRODUCTION

During the course of a detailed study of the biology of sand crabs () along the south west coast of India (Kerala State), the second author collected a series of 17 mole crabs belonging to the Hippa Fabricius, 1787. On close examination this material proved to belong to a hitherto unknown species, which we describe below. The collecting locality was characterised by a substratum of silicious sand (200-600 11) with very little silt, strong wave action and typical marine condi- tions. The tides in this region are of a mixed type with a strong semidiurnal in- fluence. The currents along the Kerala coast flow northwards during November to January and southwards from May to early September. Wave action is continuous. The wave frequency is about one wave per 8 to 10 seconds. The beach investigated showed an extensive berm.

Hippa indica new species (figs. 1-2) Material. - Sanghumugom Beach near Trivandrum, 8°26'N 76°55'E; collected during March, May and August 1980, from higher levels of the intertidal zone. Holotype (Q ovig., CL 7 mm) deposited in Indian Museum, Calcutta. Paratypes (4 99 non-ovig., CL 4 to 5 mm; 3 9 9 ovig., CL 5 to 7 mm) deposited in Indian Museum and Allan Hancock Foundation. - Description. Carapace slightly less than one and one-third times as long as broad, widest at distal end and narrowing anteriorly; surface covered com- pletely and more or less evenly with small setiferous pits, these closely set and rounded or (slightly) transversely elongate, not forming striations or noticeably oblique rows near lateral margins. Anterior margin between eyes straight or shallowly concave, with row of fine, plumose setae; orbital margin slightly con- vex, forming an even curve with low, rounded outer orbital lobe. 287

Fig. 1. Hippa indica, new species. A, in dorsal view; B, animal in ventral view; C, frontal part of carapace; D, carapace in lateral view; E, left antennule; F, left antenna. Scales = 0.5 mm. (Part of setation omitted.)