Chondracanthid copepods parasitic on flatfishes of Kerala, India Author Ju-Shey text Journal of Natural History 2000 2000-05-30 34 5 709 735 http://dx.doi.org/10.1080/002229300299372 journal article 10.1080/002229300299372 1464-5262 Heterochondria pillaii Ho, 1970 (®gures 7±8) Material examined . Thirty four adult mm (each with attached l) found on gill ®laments of their hosts: 25 from Pseudorhombus triocellatus (Bloch) (12 collected on 29 July 1994 , two on 12 October 1994 and 11 on 29 April 1995 ), four from P. elevatus Obilby collected on 12 October 1994 , two from P. arsius (Hamilton) collected on 29 April 1995 , one from P. javanicus (Bleeker) collected on 12 October 1994 , one from Cynoglossus dubius (Regan) collected on 14 February 1994 and one from C. lida collected on 26 December 1994 . Female. Body (®gure 7A) elongated, cylindrical and measuring 2.52±5.71 mm long. Head (®gure 7B) longer than wide, 910Ö 482 m m (not including ināted antennule), with two lateral protrusions in front and one similar but smaller protrusion in rear. Neck region (®rst pediger) not marked oOE from trunk. Genital double somite (®gure 7C) wider than long and bearing a lateral seta in egg sac attachment area. Abdomen (®gure 7C) distinctly longer than wide. Caudal ramus (®gure 7C) a spiniform, pointed process bearing three setae and a medial knob. Egg sac lengths variable, ranging from less than one-half of to more than twice body length. Antennule (®gure 7D) ¯eshy, ināted, with a subterminal, posteroventra l protrusion; armature being 1-1-8 (®gure 7E, from proximal to distal). Antenna (®gure 7F) two-segmented; proximal segment small, bearing a sclerotized process at base of terminal segment, which is a slender claw with corrugated surface in the distal third. Labrum (®gure 7G) with denticles on posterior margin. Mandible (®gure 7H) twosegmented; terminal blade with a row of 22 to 26 teeth on convex (inner) side and two rows of about 25 teeth on concave (outer) side. Maxillule (®gure 7I) a small ¯eshy lobe tipped with two short setae and a patch of spinules. Maxilla (®gure 7J) two-segmented; ®rst segment large but unarmed, second segment bearing in basal region one small, simple seta and one large seta with hyaline tip, and a row of about 30 teeth on terminal process. Maxilliped (®gure 7K) three-segmented; ®rst segment largest but unarmed, second segment expanded distally and bearing two rows of spines with terminal claw bending between them. Leg 1 (®gure 8A) larger than leg 2 (®gure 8B); both legs constructed on same plan with a long outer seta, a patch of spinules on distal surface, a small terminal seta, and a small nipple-like bud on medial surface. FIG. 7. Heterochondria pillai Ho. Female: (A) habitus of adult, dorsal; (B) head, dorsal; (C) genito±abdomen, ventral; (D) antennule; (E) terminal part of antennule; (F) antenna; (G) labrum; (H) mandible; (I) maxillule; (J) maxilla; (K) maxilliped. Scale bars: 0.5 mm in (A); 0.2 mm in (B); 0.1 mm in (C, F); 0.05 mm in (D, G, K); 0.02 mm in (E, H±J). FIG. 8. Heterochondria pillai Ho. Female: (A) leg 1; (B) leg 2. Male: (C) habitus of adult; lateral; (D) genito±abdomen, ventral; (E) antennule; (F) antenna; (G) labrum; (H) mandible; (I) paragnath; (J) maxillule; (K) maxilla; (L) maxilliped. Scale bars: 0.05 mm in (A±C); 0.01 mm in (D±L). Male. Body (®gure 8C) 292 m m long, with swollen cephalosome and cylindrical metasome and urosome. Genital somite with usual ventrolateral ridges and indistinguishably fused with abdomen (®gure 8D). Caudal ramus as in female but naked. Antennule (®gure 8E) reduced to a small rod tipped with few setae. Antenna (®gure 8F) two-segmented; terminal segment a short, stout claw. Labrum (®gure 8G) roughly as in female. Mandible (®gure 8H) with fewer teeth on terminal blade, 15 on convex side and six on concave side. Paragnath (®gure 8I) a small, spinulose lobe. Maxillule (®gure 8J) as in female but lacking spinules. Maxilla (®gure 8K) with seven teeth on terminal process. Maxilliped (®gure 8L) generally as female except terminal teeth on second segment occurring in two patches rather than in two rows. Leg 1 (®gure 8C) reduced to a simple spiniform seta as in Acanthochondria zebriae (see ®gure 2J). Leg 2 absent. Remarks. The most characteristic feature of H. pillaii is the possession of a nipple-like bud on the medial surface of leg 1 in the female (see ®gure 8A) and a small, rod-like antennule in the male (®gure 8E). Both of them are rather unusual for the species of Heterochondria . If the nipple-like bud on the female leg 1 was considered to represent the modi®ed, reduced endopod, then H. pillaii could have been placed in Bactrochondria . However, the structure of leg 2 in the female of H. pillaii will de®nitely preclude such consideration. H. pillaii is the most common chondracanthid copepod parasitic on the six species of ¯at®shes in Kerala ( table 1 ). Thus, it is not surprising to see it being reported on Pseudorhombus arsius (Hamilton) from the Persian Gulf by Ho and Sey (1996) .