Hirodai ohtsukai Aneesh & Helna & Kumar & Venmathi Maran 2023, gen. n. et sp. n.
Creators: name: Aneesh, Panakkool Thamban
name: Helna, Ameri Kottarathil
name: Kumar, Appukuttannair Biju
name: Venmathi Maran, Balu Alagar
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Copepoda
Cyclopoida
Uranoscopicolaidae
Hirodai
Hirodai ohtsukai

description: Hirodai ohtsukai gen. n. et sp. n.
(Figures 1–11)
https:// urn:lsid:zoobank.org:act: A55DC0F1-6057-4B1A-A449-E164ACED3156
Material examined
24 ♀♀; 9♂♂
Type material. Holotype – 1 ♀ (6 mm) (Reg. No. ZSI / WGRC / IR / INV / 22066), from Uranoscopus guttatus from Colachel, Tamil Nadu coast, south-west coast of India, coll. P.T. Aneesh and A.K. Helna on 17 March 2018. Paratypes – All from Uranoscopus guttatus from Colachel, Tamil Nadu coast, south-west coast of India, coll. P.T. Aneesh and A.K. Helna, 1 ♀ (5 mm) (Reg. No. ZSI / WGRC / IR / INV /22067), coll. on 28 May 2018; 1 ♂ (2.6 mm) (Reg. No. ZSI / WGRC / IR / INV / 22068) coll. on 17 March 2018; 1 ♀ (6 mm) (Reg. No. ZSI / WGRC / IR / INV / 22,069) coll. on 14 September 2018; 1 ♀ (immature) (4.5 mm) (Reg. No. CAH / INV / COP 0101) coll. on 7 November 2018; 1 ♀ (6.5 mm) (Reg. No. CAH / INV / COP 0102) coll. on 15 February 2019; 1 ♂ (2.7 mm) (Reg. No. CAH / INV / COP 0103) coll. on 17 January 2019; 1 ♀ (6.5 mm) (partially disected) (Reg. No. CAH / INV / COP 0104) coll. on 15 February 2019.
Type host. Uranoscopus guttatus Cuvier, 1829 (Uranoscopidae).
Type locality. Colachel, Tamil Nadu coast, south-west coast of India (8°10ʹ12″ N, 77° 15ʹ11″ E).
Description of female. (Figures 1–5, 11) Body slender, elongate, 3 times as wide as long (widest at Cephalosome, ventrolateral processes not included), with distinct segmentation, total body length 5–6 mm (without egg sacs, from anterior margin of cephalosome to distal end of rami) (n = 6). Cephalosome 1.5 times as wide as long. Pedigerous somites subequal in length, narrower than cephalothorax, gradually decreasing in width posteriorly, only leg 5 visible dorsally. Pedigerous with 5 somites, somites 1–4 each bearing one pair of elongated, fusiform, pedunculate ventrolateral processes (Figures 1–2), all processes subequal in length and width. All somites wider than long; decreasing width from 1 to 5 (ventrolateral processes not included); segments 1 to 5 are 2.9 times, 2.6 times, 2.5 times, 2.1 times, and 1.7 times as wide as long, respectively. Genital double somite 0.58 times as wide as last trunk segment. Genital double somite with pair of setules in mid-ventral region bearing egg sacs. Abdomen, distinctly segmented, 0.18 times as long as total body length, with 4 free somites. First three somites 2 times as wide as long, anal segment as long as wide and longer than others. Caudal ramus (Figure 5f) 5 times longer than wide, with 1 small seta on distolateral, and apex with 2 long papilla and 2 small setae on either side of the papilla. Egg sacs (Figure 1b, d, e) longer than abdomen; eggs multiseriate.
Antennule (Figures 3a, 4a) 6-segmented, extending beyond lateral limit of cephalothorax. Basal segment widest and longest, as wide as long; most narrow at terminal segment; segment 2, 0.85 times as long as segment 1, 1.5 times as long as wide, segments gradually decreasing in length from 1–6. All segments with marginal setae, basal segment with 9 setae on lateral margin, 2nd segment with cluster of 13 setae along lateral margin, 3rd segment with 2 proximal and 1 distal setae, 4th segment with 8 setae, 5th segment with 3 setae on lateral margin, 6th segment with 3 terminal setae.
Antenna (Figures 3b, 4b–d) uncinated, 2-segmented, basal segment with 1 accessory process, armed with 2 papillae, one basal and the other terminal, and 3 setae; distal segment modified into terminally bent hook.
Mandible (Figures 3c, 4e), represented by falcate blade, apically curved; furnished with many spinules on both margins.
Maxillule (Figures 3f, 4g), vestigial, lobate, tipped with apical spinules.
Maxilla 2-segmented (Figures 3d–e, 4f), first segment unarmed; terminal segment with ventral robust seta at middle, apex armed with bunch of spinules.
Maxilliped vestigial (Figures 3g, 4h).
Five pairs of legs; legs 1–4 biramous, basis without setae and spines, exopodite and endopodite 3-segmented, armed with plumose setae and spines (see Table 1 for setal formula of rami of various legs), leg 5 uniramous.
Leg 1 (Figure 5a) basis without setae and spines; exopod, segments 1 and 2 each on inner corner with 1 plumose seta, outer distal corner with 1 small spine; terminal segment outer margin with 6 spines, inner margin with 4 long plumose setae; endopod, first and second segments outer distal corner with 1 short spine and inner distal corner with 1 long plumose seta, third segment free outer margin with 3 short spines, and inner margin with 4 long plumose setae.
Leg 2 (Figure 5b) exopod, segments 1 and 2 each outer distal corner with 1 small spine; terminal segment outer margin with 4 short and 2 median spines, inner margin with 5 long plumose setae; endopod, first and second segment outer distal corner with 1 short spine and inner distal corner with 1 and 2 long plumose setae, respectively, third segment free outer margin with 4 short and 2 median spines, and inner margin with 4 long plumose setae.
Leg 3 (Figure 5c) exopod, segments 1 and 2 each outer distal corner with 1 small spine, segment 2 inner margin with 1 long plumose seta; terminal segment outer margin with 6 short and 2 median spines, inner margin with 4 long plumose setae; endopod, first and second segments outer distal corner with 1 short spine and inner distal corner with 1 and 2 long plumose setae respectively, third segment outer margin with 4 short and 1 median spines, and inner margin with 4 long plumose setae.
Leg 4 (Figure 5d) exopod, segments 1 and 2 each outer distal corner with 1 small spine; terminal segment outer margin with 6 short and 2 long spines, inner margin with 5 long plumose setae; endopod, first and second segments each outer distal corner with 1 short spine and inner distal corner with 1 and 2 long plumose setae, respectively, third segment outer margin with 4 short and 2 long spines, and inner margin with 4 long plumose setae.
Leg 5 (Figure 5e) uniramous, represented by long lobe, apical margin having 3 small spines.
Description of male. (Figures 6–11) Smaller than female (0.45 times as long as female). Body slender, elongated, 3.5 times as wide as long (widest at Cephalosome), with distinct segmentation, total body length 2.4–2.6 mm (from anterior margin of head to distal end of rami) (n = 3). Cephalosome, 1.4 times as wide as long. Pedigerous somites subequal in length, narrower than cephalothorax, gradually decreasing in width posteriorly; only leg 5 visible dorsally, as in female. Pedigerous with 6 somites (including the genital double somite), without ventro-lateral processes (Figures 6, 7 a–b, 11). Abdomen distinctly segmented, 0.45 times as long as total body length, with 4 free somites. Caudal ramus (Figures 9f–h, 10f–h) 6 times longer than wide, with 1 small seta disto-laterally, and apex with 2 long papillae and 2 small setae on either side of the papilla; both papillae apically trifurcate.
Antennule (Figures 7c, 8a, 9a) and antenna (Figures 7d, 8b) similar to that of females, the accessory process armed with 1 papilla. Mandible absent. Maxilla 1 and maxilla 2 similar to that of females (Figures 7e, 8d–e). Maxilliped well developed and very prominent, basal segment armed with 2 spinules at inner distal margin; apical segment prehensile, inner margin armed with many spinules, lateral margin with one row of denticles (Figures 7f, 8c, f, 9b).
Five pairs of legs; legs 1 – 4 biramous, basis without setae and spine, exopodite and endopodite 3-segmented, armed with plumose setae and spines; leg 5 uniramous (Figures 9c–e, 10a–e). Legs similar to those of females, with only differences in setal formula of rami of various legs (Table 2).
Size
Ovigerous female: 5–6 mm; male: 2.4–2.6 mm.
Colour
Live specimens white.
Host
Known only from the type host Uranoscopus guttatus Cuvier, 1829.
Distribution
Known only from the type locality Colachel, Tamil Nadu coast, south-west coast of India (8°10ʹ12″ N; 77°15ʹ11″ E).
Etymology
This species is named in honour of Dr Susumu Ohtsuka, Professor, Graduate School of Integrated Sciences for Life, Hiroshima University, a well-known copepodologist, ecologist and marine biologist.
Species remarks
Hirodai ohtsukai sp. n. is identified by the generic characters, especially the body possessing 4 pairs of ventrolateral processes corresponding to the first four pedigerous somites, 6-segmented antennule, unusual antenna and maxilla, genital opening ventral, multiseriate egg sacs, unsegmented and reduced maxilliped in the adult female, caudal ramus with 2 long and 2 small terminal papillae, legs 1 to 4 biramous with 3-segmented rami with setae, and uniramous and unsegmented fifth leg.
Ecological remarks
In the present study, we have examined individuals of the host fish from different localities along the south-west coast of India. A total of 1013 individuals of U. guttatus were examined from four available localities along the south-west coast of India. Of these, only 19 individuals were infested with Hirodai ohtsukai gen. n. et sp. n. The prevalence was 1.9, and all were obtained from Colachel, Tamil Nadu, south-west coast of India (Table 3), suggesting that environmental factors may have some influence in triggering the infestation. A total of 24 females and 9 males were recovered from these 19 infested host fish, with intensity ranging from 1 to 4. All recovered females were reproductively active, evident from the filled/filling/empty egg sacs. Each recovered male was found attached to the female using its well-developed maxilliped. The female Hirodai ohtsukai gen. n. et sp. n. specimens were obtained from the floor of the buccal cavity over the gill raker of U. guttatus.
description: Published as part of 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, pp. 1495-1515 in Journal of Natural History 57 (33 - 36) on pages 1498-1507, DOI: 10.1080/00222933.2023.2259556, http://zenodo.org/record/10602657