Hirodai ohtsukai, Aneesh & Helna & Kumar & Venmathi Maran, 2023
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publication ID |
https://doi.org/ 10.1080/00222933.2023.2259556 |
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DOI |
https://doi.org/10.5281/zenodo.10469459 |
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persistent identifier |
https://treatment.plazi.org/id/03C387BF-2F60-3F3E-FE30-FA29FEDD3BE2 |
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treatment provided by |
Plazi |
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scientific name |
Hirodai ohtsukai |
| status |
gen. n. et sp. n. |
Hirodai ohtsukai View in CoL gen. n. et sp. n.
( Figures 1–11 View Figure 1 View Figure 2 View Figure 3 View Figure 4 View Figure 5 View Figure 6 View Figure 7 View Figure 8 View Figure 9 View Figure 10 View Figure 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 View Figure 1 View Figure 2 View Figure 3 View Figure 4 View Figure 5 , 11 View Figure 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 View Figure 1 View Figure 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 View Figure 5 ) 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 View Figure 1 ) longer than abdomen; eggs multiseriate.
Antennule ( Figures 3a View Figure 3 , 4a View Figure 4 ) 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 View Figure 3 , 4b–d View Figure 4 ) 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 View Figure 3 , 4e View Figure 4 ), represented by falcate blade, apically curved; furnished with many spinules on both margins.
Maxillule ( Figures 3f View Figure 3 , 4g View Figure 4 ), vestigial, lobate, tipped with apical spinules.
Maxilla 2-segmented ( Figures 3d–e View Figure 3 , 4f View Figure 4 ), first segment unarmed; terminal segment with ventral robust seta at middle, apex armed with bunch of spinules.
Maxilliped vestigial ( Figures 3g View Figure 3 , 4h View Figure 4 ).
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 View Table 1 for setal formula of rami of various legs), leg 5 uniramous.
Leg 1 ( Figure 5a View Figure 5 ) 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 View Figure 5 ) 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 View Figure 5 ) 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 View Figure 5 ) 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 View Figure 5 ) uniramous, represented by long lobe, apical margin having 3 small spines.
Description of male. ( Figures 6–11 View Figure 6 View Figure 7 View Figure 8 View Figure 9 View Figure 10 View Figure 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 View Figure 6 , 7 a–b View Figure 7 , 11 View Figure 11 ). Abdomen distinctly segmented, 0.45 times as long as total body length, with 4 free somites. Caudal ramus ( Figures 9f–h View Figure 9 , 10f–h View Figure 10 ) 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 View Figure 7 , 8a View Figure 8 , 9a View Figure 9 ) and antenna ( Figures 7d View Figure 7 , 8b View Figure 8 ) 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 View Figure 7 , 8d–e View Figure 8 ). 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 View Figure 7 , 8c, f View Figure 8 , 9b View Figure 9 ).
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 View Figure 9 , 10a–e View Figure 10 ). Legs similar to those of females, with only differences in setal formula of rami of various legs ( Table 2 View 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 View 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 .
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