Hirodai, Aneesh & Helna & Kumar & Venmathi Maran, 2023

Aneesh, Panakkool Thamban, Helna, Ameri Kottarathil, Kumar, Appukuttannair Biju & Venmathi Maran, Balu Alagar, 2023, Proposal of a new family for Hirodai ohtsukai gen. n. et sp. n. (Crustacea: Copepoda) infesting Uranoscopus guttatus Cuvier, 1829 (Perciformes: Uranoscopidae) from the south-west coast of India, Journal of Natural History 57 (33 - 36), pp. 1495-1515 : 1497-1498

Genus Hirodai gen. n.

https:// urn:lsid:zoobank.org:act:20362676-B00C-4E81-8D70-DF10DEEFD21C

Type species

Hirodai ohtsukai sp. n. original designation.

Etymology

The name of the new genus is an abbreviation of the name ′Hiroshima University̍ (– Hiro, Hiroshima plus – dai, daigaku in Japanese, University in English ), which is a Japanese national university located in Higashi Hiroshima City, Hiroshima Prefecture, Japan. It is the name of the home institute of the first author, PTA. The gender is feminine.

Diagnosis

Adult female. Body (5–6 mm Tolal Length (TL), without egg sacs, from anterior margin of head to distal end of rami) elongate, cyclopiform; pedigerous somites with 4 pairs of elongated ventrolateral processes. Antennule 6-segmented, all segments with marginal setae. Antenna 2-segmented, basal segment armed with 1 accessory process; distal segment modified into terminally bent hook. Mandible, represented by blade, apically curved with many marginal spinules. Maxilla 2-segmented, first segment unarmed; terminal segment with 1 robust ventral seta at middle, apex armed with bunch of spinules. Maxilliped reduced. First four pairs of legs are biramous, with 3-segmented rami. Leg 5 uniramous, indistinctly 2-segmented or fused to form long lobe. Leg 6 absent. Genital double somite with genital opening on ventral surface. Egg sac multiseriate.

Adult male. Smaller than female (0. 45 times as long as female). Body (2.4–2.6 mm TL) cyclopiform, with distinct segmentation, attached to female by maxilliped. Pedigerous somites without ventrolateral processes. Genital double segment with usual posteroventral ridges. Abdomen with 4 somites. Legs and caudal ramus as in female. Terminal long papilla of the caudal ramus with 2 small trifurcating papillae.

Remarks

The structure of the general cyclopoid body, mouthparts, and other appendages identifies the new species, Hirodai ohtsukai , as a member of Cyclopoida and Ergasilida . The genus Hirodai gen. n. can be well separated from all other known cyclopoid families by the following two characteristics: (1) 2-segmented maxilla, where the first segment is unarmed; the terminal segment has a ventral robust seta at the middle, the rounded apex is armed with a bunch of spinules on both surfaces, except in the inner middle portion; (2) maxilliped is vestigial in female and 3-segmented in male. Hirodai gen. n. possesses the following combination of characteristics: (1) pedigerous somites with 4 pairs of elongated ventrolateral processes; (2) genital double somite is 0.7 times as wide as 5 th segment; 2.1 times as wide as long; genital opening ventrally; (3) egg sac multiseriate; (4) maxilliped unsegmented and reduced in the adult female; (5) caudal ramus with 2 long and 2 small terminal papillae; (7) legs 1 to 4 biramous with 3-segmented rami armed with setae, fifth leg uniramous and unsegmented, leg 6 absent. To the best of our knowledge, of the 69 families of Ergasilida ( Uyeno 2022; Walter and Boxshall 2023), none displays either of the two key characters (2-segmented maxilla, the terminal segment with a ventral robust seta at the middle, the rounded apex is armed with a bunch of spinules on both surfaces, except in the inner middle portion (3-segmented and only the outer margin is denticulated in remaining Cyclopoida ); maxilliped is vestigial in female and three segmented in male (all other copepods of Cyclopoida possess 3-segmented maxilliped in both sexes except the family Ergasilidae which is completely absent in female). These unique characters (structure of maxilla and maxilliped) along with the combination of morphological characters makes it difficult to place the new genus in any one of the existing cyclopoid families, and hence we propose to establish the family Uranoscopicolaidae fam. n. for the new genus and species.