Acanthochondria krishnai, Aneesh & Helna & Kumar, 2020

Aneesh, Panakkool Thamban, Helna, Ameri Kottarathil & Kumar, Appukuttannair Biju, 2020, New species of Acanthochondria Oakley, 1930 and Chondracanthus Delaroche, 1811 (Copepoda: Cyclopoida: Chondracanthidae) parasitizing marine fishes from Indian waters, Nauplius (e 2020014) 28, pp. 1-21 : 2-9

Acanthochondria krishnai sp. n.

( Figs. 1–6 )

Zoobank: urn:lsid:zoobank.org:act:F26FCD3B-A7DC-45E3-AE42-F8B9D0ED693A

Material examined: 23 females (16 ovigerous), all with immature/mature males.

Typematerial. Holotype: 1 female (17 mm) (ZSI/ WGRC /IR/INV/11733), from Uranoscopus guttatus Cuvier , from Muttom , southwest coast, India, coll. P. T. Aneesh on 17 March 2018 . — Paratypes: same information as holotype, 1 female (15 mm) (ZSI/ WGRC /IR/INV/ 11734; 1 male (0.5 mm) (ZSI/ WGRC /IR/INV/14048).

Description. Female ( Figs. 1–4 ): Body long and slender (16–18 mm) (excluding egg strings; from anterior margin of head to distal end of posterior processes), divisible into short head, much elongated neck, stout trunk with prominent constrictions on posterior half, as long as neck, bearing a pair of posterior processes, small genito-abdomen and abdomen with the prominent process which extends to the posterior tip of caudal rami. Cephalon, small, 1.2 times longer than wide, attached to neck; posteroventral region swollen, with mouthparts. Neck greatly elongated (8–9 mm) and gradually jointed into trunk. Trunk as long as neck, postero lateral margin with pair of long processes (4–5.5 mm) directed laterally, posterolaterally, or posteriorly. Genito-abdomen (0.45–0.5 mm, long; total length including the median projection, the abdomen), funnel-shaped, longer than wide, basally wider (0.28–0.30 mm wide), with median projection (the abdomen) (0.25–0.28 mm long and 0.06 mm wide) gradually narrowing posteriorly, with curved apex. Genital complex with pair of setules in midventral region bearing egg strings.

Egg strings cylindrical, not coiled and longer than trunk; eggs multiseriate. Number of eggs per string ranged from 170 to 240, dependent on length of the string. Genital complex carrying pair of conical rami with numerous spinules on terminal portion.

Antennule cylindrical and fleshy, without division, basally swollen, and distally slender with few terminal setae. Antenna, usual form with heavily sclerotized and unarmed basal segment and strongly curved, pointed terminal claw. Mandible with many teeth (55–60) on convex side and 40–44 teeth on concave side. Maxillule with spinulose inner-terminal surface; distal margin with 2 unequal setae. Two-segmented maxilla; first segment greatly broad and unarmed; terminal segment with more or less equal robust seta in basal region, and the outer margin claw-like, armed with row of 28–32 denticles.Maxilliped 3-segmented; first segment stout, largest, unarmed; second segment with two patches of denticles on medial surface and protruded medio-distal corner, partially overlapping base of the distal segment; terminal segment ending in curved claw-like structure with small, sub-terminal hooklet on inner surface. Legs biramous, protopod with one seta, leg 1 (0.25 mm); both rami bearing spinules/pectinate scales on terminal portion. Leg 2 (0.4 mm) much longer than (1.8 times) leg 1.

Male ( Figs. 5–6 ): Body, 0.45 mm long (excluding caudal rami), 0.25 mm wide, ventrally curved, cephalothorax, more than half the length of total body. Metasome cylindrical, with indistinct metamerism. Genital segment with pair of ventral genital ridges. Caudal ramus similar to that of female.

Antennule elongated, with armature formula 2, 1, 2, 2, and 8–9. Antenna, solid, robust and strongly curved, sharp claw; with seta on dorso-lateral surface. Mandible with 16–18 teeth on convex side and 12–14 teeth on concave side. Maxillule with 2 setae, more or less similar to female. Maxilla without teeth on terminal process. Maxilliped article 2 with few denticles. Legs bilobate, leg 1 larger than leg 2; with few long lateral setae, larger in leg 1; endopods reduced to lobes.

Body size: Female (15–18 mm); male (0.45–0.50 mm).

Figures

Figure 1. Acanthochondria krishnai sp. n., female from Uranoscopus guttatus Cuvier. A, B. Dorsal view. C. Ventral view.

Figure 2. Acanthochondria krishnai sp. n., holotype, female from Uranoscopus guttatus Cuvier.A. Dorsal view.B. Ventral view. C, D. Cephalon, dorsal and ventral views. E. Antennule. F. Antenna.

Figure 3. Acanthochondria krishnai sp. n., non-type female from Uranoscopus guttatus Cuvier. A. Cephalon ventral view showing cephalic appendages. B. Antennule (arrow). C. Antennules (arrows). D. Cephalic appendages. E. Leg 1. F. Leg 2. G–J. Genitoabdomen. G. Lateral view with rami. H. Ventral view with rami. I. Dorsal view with male.J. With rami. (a1- antennule, a2- antenna, mxp- maxilliped, max- maxilla; L1- leg 1, L2- leg 2, m- male, r- rami).

Figure 4. Acanthochondria krishnai sp. n., paratype, female from Uranoscopus guttatus Cuvier. A. Mandible. B. Maxillule.C. Maxilla. D. Maxilliped. E. Maxilliped apex. F. Leg 1. G. Leg 2. H, I. Genito-abdomen with rami, ventral and ventro-lateral views. J. Rami.

Figure 5. Acanthochondria krishnai sp. n., non-type male from Uranoscopus guttatus Cuvier. A. Habitus lateral view. B. Antennule. C. Antenna.

Figure 6. Acanthochondria krishnai sp. n., non-type male from Uranoscopus guttatus Cuvier. A. Habitus lateral view. B. Antennule. C. Antenna. D. Mandible. E. Maxillule. F. Maxilla. G. Maxilliped. H. Leg 1. I. Leg 2. J. Lateral view of genito-abdomen. K. Ventral view of genito-abdomen.