Protochondracanthus trilobatus, (Pillai, 1964)

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 : 732-734

publication ID	https://doi.org/10.1080/002229300299372
DOI	https://doi.org/10.5281/zenodo.10237839
persistent identifier	https://treatment.plazi.org/id/7A57A021-FFBD-FF91-FEFA-FEA1521EFA72
treatment provided by	Carolina
scientific name	Protochondracanthus trilobatus
status

Treatment

Protochondracanthus trilobatus ( Pillai, 1964)

( figures 15-16 View FIG View FIG )

Material examined. Two adult ♀♀ (each with attached ♂) from gill fi laments of Psettodes erumi : one collected on 29 July 1994 and another on 12 October 1994.

Female. Body ( figure 15A View FIG ) elongated, 2.86 mm long. Head globose, but wider than long. First pediger transformed into a short neck, bearing a pair of small, tripartite processes on ventral surface where leg 1 attaches. Remaining pedigers fused into a long cylindrical trunk, bearing a pair of long, lateral processes in front ( figure 15A View FIG ) and another pair of short, posterior processes at end ( figures 15A, B View FIG ). Genital double somite ( figure 15B View FIG ) wider than long, 104✕ 142 μ m, bearing a long seta in egg sac attachment area. Abdomen ( figure 15B View FIG ) wider than long, 54✕ 75 μ m. Caudal ramus ( figure 15B View FIG ) a spiniform process armed with three setae and a small tubercle. Egg sac not seen.

Antennule ( figure 15C View FIG ) with cylindrical basal portion and a short, offset, distal process; armature being 11 on basal portion and ten on distal process. Antenna ( figure 15D View FIG ) two-segmented; first segment small and unarmed, second segment a sharp, recurved hook with a minute, medial tubercle in basal region. Labrum ( figure 15E View FIG ) with a small tubercle on lateral margin. Mandible ( figure 15F View FIG ) two-segmented; terminal blade with a row of 12 teeth on convex (inner) side. Maxillule ( figure 15G View FIG ) tipped with a lobe and two short setae. Maxillule ( figure 15H View FIG ) two-segmented; basal segment large but unarmed, distal segment bearing one small, simple seta, one large seta with hyaline tip in basal region and a row of about 25 teeth on terminal process. Maxilliped ( figure 15I View FIG ) 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 a subterminal setule ( figure 15J View FIG ). Leg 1 ( figure 15K View FIG ) located at base of tripartite, ventral process in neck region and consisting of a protopod carrying a long, outer seta, an exopod armed with six setae, and an endopod tipped with two setae. Long, lateral process in anterior region of trunk equipped with a subterminal seta and four or five terminal setae ( figure 15L View FIG ).

Male. Body ( figure 16A View FIG ) globose, with posterior portion strongly bent forward. Genital somite and abdomen indistinguishably fused ( figure 16B View FIG ). Caudal ramus ( figure 16B View FIG ) a short spinulose process. Antennule ( figure 16C View FIG ) fi liform, armature being 1-1-1-7. Antenna ( figure 16D View FIG ) two-segmented; terminal hook short and stubby. Mandible ( figure 16E View FIG ) with a row of 13 teeth on convex margin of terminal blade. Maxillule ( figure 16F View FIG ) tipped with a blunt knob and 2 setae. Maxilla ( figure 16G View FIG ) as in female except for fewer teeth (about ten) on terminal process. Maxilliped ( figure 16H View FIG ) constructed as in female only stubbier. No traces of legs.

Remarks. Although P. trilobatus and P. alatus were often found occurring together on flatfishes, their appearances are quite different. The former, though smaller, can not be mistaken for the juvenile of the latter.

In the female, T. trilobatus lacks the cephalic and oral process and has shorter neck and trunk processes. These differences are discernible without dissection of the specimen. There are also differences in the fi ne anatomy, visible only after dissection. The present species is distinguishable from P. alatus in lacking a vermiform process on the antennule (see figure 2E View FIG ), having fewer teeth on the mandible (12 vs. 36) and maxilla (45 vs. 60), and bearing two setae (instead of none) on the endopod of leg 1. The male of P. trilobatus also has fewer teeth on the mandible (13 vs. 25) and maxilla (10 vs. 22) than those of P. alatus . Additionally, it lacks an outer knob on the antenna (see figure 14E View FIG ) and leg 1 is entirely missing.

The tripartite body process in the neck region of Protochondracanthus represents, perhaps, the modi fi ed coxal region of leg 1. This is more apparent in P. trilobatus then in P. alatus . Due to the tremendous expansion and elongation of the middle one of these three lobes in P. alatus (see figure 13G View FIG ), it looks more like a body process then a coxal expansion. The true identity of these lobes can only be corroborated through studies on their maturation transformation.