Proclavellodes pillaii gen. et sp. n. (Copepoda: Lernaeopodidae) from South India

Abstract

Proclavellodes, a new genus of Clavellinae (Copepoda: Lernaeopodidae), is described and illustrated. The genus is based on female P. pillaii sp. n., from the gill rakers of Gazza minuta, taken in Trivandrum, South India. It is characterized mainly by the structure of its second antenna and by the dental formula of its mandible. Some months ago, Dr. N. K. Pillai of Trivandrum, South India, sent to the author several specimens of a female lernaeopodid copepod. The specimens obviously belonged to the subfamily Clavellinae, but could not be placed in any of the known genera. Following careful investigation of the morphology of the specimens, the author decided to place them in a new genus, Proclavellodes, under the name P. pillaii sp. n. The specimens, both entire and dissected, were examined with the aid of phase contrast illumination, under magnifications up to x 900. Berlese's fluid was used as mountant and clearing agent. Stains were not employed. Each appendage was removed and examined separately. All drawings were made freehand with the aid of an eyepiece graticule. Diagnosis of the genus Proclavellodes Clavellinae. First antenna of normal lernaeopodid type. Second antenna bending in a characteristic ventral curve. Mandibular formula varied, with at least one secondary tooth. First maxilla as in Clavellodes. Second maxilla with aliform lateral expansion which, however, is rather less well developed than in Clavellodes. Type species: P. pillaii. The name Proclavellodes indicates the relationship of the new genus to Clavellodes. The gender of the new genus is masculine. The specific name refers to Dr. N. K. Pillai. Proclavellodes pillaii sp. n. (Figs. 1-16) Record of specimens: Eight females, most of them ovigerous, were found by Dr. N. K. Pillai in Trivandrum, South India, on 17 July 1960. One of them is designated the holotype of the species, two others the paratypes. These specimens are deposited in the British Museum, London, Reg. No. B.M.(N.H.) 1967.4.6.1. The remaining specimens are held by Dr. Pillai. Host: Gazza minuta (Bloch, 1797). Habitat: Gill rakers. Received for publication 24 July 1967. Description of the female General appearance (Figs. 1, 2). Clavellinae. Cephalothorax long, slender, curving and deflected dorsally, forming acute angle with long axis of trunk. Terminal head without distinct carapace. Lateral, aliform swellings on both sides of second maxillae. Only slight constriction below base of cephalothorax. Trunk not externally segmented, slightly flattened dorsoventrally, rather wider near posterior extremity. Lateral margins of trunk nearly parallel. Posterior margin of trunk smooth, without processes or appendages, above its center a small tubercle with anal slit. No traces of anal laminae. Oviduct orifices lateral to anus. Egg-sacs multiseriate, eggs spherical. Dimensions (in mm), based on measurements of four specimens, are as follows: Cephalothorax length 1.40 to 1.80, width 0.16 to 0.20. Trunk length 1.08 to 1.40, width 0.44 to 0.60. Egg-sac length 1.48 to 1.60, width 0.20. Appendages. First antenna (Figs. 4-6) short, not clearly segmented, with noticeable division at about midlength. Basal half more robust, thicker than distal half. Distal end of basal part with fairly long, dorsomedial seta (Fig. 4). Distal half cylindrical, with rounded tip. Apical armature of four setae and one short, spine-tipped tubercle. Principal feature of armature is medial seta 4 (Figs. 5, 6), with blunt tip. Tubercle 1 (Figs. 5, 6) directly ventral to 4. Long and slender, lateral seta 6, usually points away from head. On or near the apex two structures, x and y. Although the author was unable to make certain that they are joined at bases, it is possible that they correspond to bifid seta 5 of other Clavellinae (cf. Kabata, 1963a). Second antenna (Figs. 7-10) conforms to pattern of Clavellinae only in broad outlines. Sympod robust, heavily sclerotized, definitely curved, concave side ventralmost. Rami point ventrad, exopod dorsal to endopod. Exopod bulbous, peduncular, outer margin covered with minute prickles (hardly noticeable in some specimens). Prominent seta on lateral aspect, near base. Endopod two-segmented, about as long as exopod, but less robust. Development of endopod less advanced than in most Clavellinae, resembling rather Charopinus group and primitive freshwater genera (e.g., Salmincola). Its apical armature has four elements. Principal feature is a strong spine 1 (Figs. 8, 9) with some