Protochondracanthus alatus, (Heller, 1868)

Ho, Ju-Shey, Kim, Il-Hoi & Kumar, A. Biju, 2000, Chondracanthid copepods parasitic on flatfishes of Kerala, India, Journal of Natural History 34 (5), pp. 709-735 : 728-732

Protochondracanthus alatus (Heller, 1868)

( figures 12-14 )

Material examined. Nine adult ♀♀ (each with attached ♂) from gill fi 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 ( figures 12A,B ) elongated, measuring 4.04 to 4.71 mm long. Head ( figure 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 ( figures 12C , 13C ). First pediger transformed into a short neck, bearing a pair of tripartite, lateral processes on both sides ( figures 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 ( figure 12D ). Both genital double somite and abdomen ( figure 12D ) distinctly wider than long. Caudal ramus ( figure 12D ) a spiniform process armed with three setae and a small tubercle. Egg sac longer than body.

Antennule ( figure 12E ) with modi fi ed, fl 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 ( figure 12F ) two-segmented; first segment small and unarmed, second segment a sharp, recurved hook with a small, medial knob in basal region. Labrum ( figure 12G ) with smooth posterior margin. Mandible ( figure 13A ) two-segmented; terminal blade with a row of 36 teeth on convex (inner) side. Maxillule ( figure 13B ) tipped with a lobe and two short setae. Maxilla ( figure 13C ) two-segmented; basal segment large but unarmed, distal segment ( figure 13D ) bearing one small, simple seta, one large seta with hyaline tip in basal region and a row of about 60 fi ne spinules on terminal process. Maxilliped ( figure 13E ) slender and three-segmented; first 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 ( figure 13F ). Leg 1 ( figure 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 five 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 ( figure 13I ).

Male. Body ( figure 14A ) 269 μ m long, with swollen cephalosome. First two pedigers separated, but remaining pedigers fused with genito -abdominal somites ( figure 14A, B ). Caudal ramus ( figure 14C ) a short, spiniform process with six short setae in basal region and spinules in distal region. Antennule ( figure 14D ) fi liform, armature being 1-1-2-3-8. Antenna ( figure 14E ) two-segmented; terminal hook with a small outer knob in basal region. Mandible ( figure 14F ) with a row of about 25 teeth on convex margin of terminal blade. Maxillule ( figure 14G ) tipped with a blunt knob and two setae. Maxilla ( figure 14H ) as in female except for smaller number of teeth (about 25) on terminal process. Maxilliped ( figure 14I ) constructed as in female only stubbier. Leg 1 represented by a bifurcate seta (see figure 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 fi able with P. alatus (by the presence of a pair of posterolateral cephalic knobs), Kirtisinghe’ s illustration is not. Kirtisinghe’ s illustration (called Protochondracanthus psettodis and given in figure 50) of the immature specimen looks like a mirror copy of P. trilobatus given here in figure 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 fi c to the bigmouth fl ounder ( Psettodes erumi ).

Figures

FIG. 12. Protochondracanthus alatus (Heller). Female: (A) habitus of adult, dorsal; (B) habitus of another adult, dorsal; (C) head and neck region, ventral; (D) posterior processes and genito-abdomen, ventral; (E) anennule; (F) antenna; (G) labrum. Scale bars: 1 mm in (A, B); 0.2 mm in (C, D); 0.05mm in (E-G).

FIG. 13. Protochondracanthus alatus (Heller). Female: (A) mandible; (B) maxillule; (C) maxilla; (D) distal segment of maxilla; (E) maxilliped; (F) terminal part of maxilliped; (G) leg 1; (H) rami of leg 1; (I) distal part of trunk process. Scale bars: 0.02mm in (A-D, F, H); 0.05mm in (E, G, I).

FIG. 14. Protochondracanthus alatus (Heller). Male: (A) habitus of adult, dorsal; (B) same, lateral; (C) caudal ramus; (D) antennule; (E) antenna; (F) mandible; (G) maxillule; (H) maxilla; (I) maxilliped. Scale bars: 0.1 mm in (A, B); 0.01mm in (C-I).

FIG. 15. Protochondracanthus trilobatus (Pillai). Female: (A) habitus of adult, dorsal; (B) genito-abdomen and posterior part of trunk, ventral; (C) antennule; (D) antenna; (E) labrum; (F) mandible; (G) maxillule; (H) maxilla; (I) maxilliped; (J) distal part of maxilliped; (K) leg 1; (L) distal part of trunk process. Scale bars: 0.5 mm in (A); 0.1 mm in (B); 0.02 mm in (C-L).