Protochondracanthus alatus, (Heller, 1868)

Ju-Shey, 2000, Chondracanthid copepods parasitic on flatfishes of Kerala, India, Journal of Natural History 34 (5), pp. 709-735 : 728-732

Protochondracanthu s alatus (Heller, 1868)

(®gures 12±14)

Material examined. Nine adult mm (each with attached l) from gill ®laments of Psettodes erumi (Bleeker and Schneider) : four collected on 20 July 1994, two on 25 October 1994 and three on 26 January 1994.

Female. Body (®gures 12A,B) elongated, measuring 4.04 to 4.71 mm long. Head (®gure 12C) composed of cephalosome only and protruded posterolaterally into a small process. A pair of vermiform processes in oral region originated at bases of maxillae (®gures 12C, 13C). First pediger transformed into a short neck, bearing a pair of tripartite, lateral processes on both sides (®gures 12C, 13G). Remaining pedigers fused into a long cylindrical trunk, bearing a pair of long, lateral processes in front, another pair of short posterior processes at end, and a vermiform process at midposterior end (®gure 12D). Both genital double somite and abdomen (®gure 12D) distinctly wider than long. Caudal ramus (®gure 12D) a spiniform process armed with three setae and a small tubercle. Egg sac longer than body.

Antennule (®gure 12E) with modi®ed, ¯eshy basal portion bearing a vermiform posteroventral process and a small knob-like setiferous terminal process; armature being 11 on basal portion and ten on terminal process. Antenna (®gure 12F) two-segmented; ®rst segment small and unarmed, second segment a sharp, recurved hook with a small, medial knob in basal region. Labrum (®gure 12G) with smooth posterior margin. Mandible (®gure 13A) two-segmented; terminal blade with a row of 36 teeth on convex (inner) side. Maxillule (®gure 13B) tipped with a lobe and two short setae. Maxilla (®gure 13C) two-segmented; basal segment large but unarmed, distal segment (®gure 13D) bearing one small, simple seta, one large seta with hyaline tip in basal region and a row of about 60 ®ne spinules on terminal process. Maxilliped (®gure 13E) slender and three-segmented; ®rst segment largest but unarmed, second segment with spinules in terminal and subterminal regions, and third segment drawn out into a pointed process with two rows of spinules in basal region in addition to a single, subterminal spinule (®gure 13F). Leg 1 (®gure 13G) located at base of tripartite, lateral process in neck region and consisting of a protopod carrying a long, outer seta, an exopod armed with ®ve spines and one seta, and a naked endopod. Long, lateral process in anterior region of trunk tipped with four tubercles with each bearing a spinule at tip (®gure 13I).

Male. Body (®gure 14A) 269 m m long, with swollen cephalosome. First two pedigers separated, but remaining pedigers fused with genito±abdominal somites (®gure 14A, B). Caudal ramus (®gure 14C) a short, spiniform process with six short setae in basal region and spinules in distal region. Antennule (®gure 14D) ®liform, armature being 1-1-2-3-8. Antenna (®gure 14E) two-segmented; terminal hook with a small outer knob in basal region. Mandible (®gure 14F) with a row of about 25 teeth on convex margin of terminal blade. Maxillule (®gure 14G) tipped with a blunt knob and two setae. Maxilla (®gure 14H) as in female except for smaller number of teeth (about 25) on terminal process. Maxilliped (®gure 14I) constructed as in female only stubbier. Leg 1 represented by a bifurcate seta (see ®gure 14B). Other legs missing.

Remarks. Both Kirtisinghe (1950) and Pillai (1964) found both ovigerous and juvenile females of P. alatus occurring together on the same host taken respectively in Sri Lanka and at Trivandrum (in Kerala). However, while Pillai’s illustration of the juvenile is readily identi®able with P. alatus (by the presence of a pair of posterolateral cephalic knobs), Kirtisinghe’ s illustration is not. Kirtisinghe’ s illustration (called Protochondracanthu s psettodis and given in ®gure 50) of the immature specimen looks like a mirror copy of P. trilobatus given here in ®gure 15A. Distinctions between these two species are given following the description of P. trilobatus .

According to Song and Chen (1976), P. alatus is also known from Hainan, China, on the same host species as from Kerala, India. Thus, as above in the case of Heterochondria similis , it is very likely that P. alatus is host speci®c to the bigmouth ¯ounder ( Psettodes erumi ).