Entomopsyllus takara, Uyeno & Johnsson, 2018

Uyeno, Daisuke & Johnsson, Rodrigo, 2018, Two new species of Siphonostomatoida (Copepoda) found on cnidarians in Tokara Islands, Southern Japan, Journal of Natural History 52 (41 - 42), pp. 2639-2652 : 2644-2649

Entomopsyllus takara sp. nov.

( Figure 3–5 )

Type material

Holotype adult male (NSMT-Cr 25853), ex Heliopora coerulea (Pallas, 1766) (Octocorallia: Helioporacea : Helioporidae ), off Maegomori Port (29°9 ʹ N, 129°11 ʹ E), Takara Island, Tokara Islands, Japan, 10 m depth, 17 September 2015, leg. D. Uyeno. Paratype: 1 adult male

(NSMT-Cr 25854), ex Distichopora violacea (Pallas) ( Hydrozoa: Anthoathecata : Stylasteridae ), locality and date same as that of holotype.

Description of holotype adult male

Body ( Figure 3 (a)) 1088 long. Prosome 1053 long, comprising cephalothorax and three free thoracic somites. Cephalothorax ( Figure 3 (a)), wider than long, 647 × 722, flattened dorsoventrally. Second to fourth pedigerous somites ( Figure 3 (a)) wider

than long; dorsal plate of fourth pedigerous somite covering urosome and caudal rami. Urosome comprising fifth pedigerous somite fused to genital somite and three postgenital somites. Genital somite ( Figure 3 (b)) wider than long, 174 × 199. Postgenital somites ( Figure 3 (b)) 3-segmented, 37 × 57, 30 × 56, and 44 × 53, respectively. Caudal rami ( Figure 3 (b,d)) 6.53 times long than wide, 115 × 18, with six setae and row of spinules on inner margin.

Rostrum absent. Antennule ( Figure 3 (e)) 13-segmented, armature formula 1, 2, 10, 2, 6, 2, 2, 4, 2, 2, 3, 3 + 1 aesthetasc, and 10; all setae naked. Antenna ( Figure 4 (a)) composed of coxa, basis, unsegmented exopod, and 2-segmented endopod; coxa and basis unarmed; exopod rod shaped, bearing several rows of hairs and two distal setae; endopod bearing proximal segment with irregular rows of hair and distal segment with terminal claw and five setae. Mandible ( Figure 4 (b)) biramous, composed of elongate inner stylet (endite) and 2-segmented outer palp bearing two distal setae. Oral cone ( Figure 4 (c)) elongate and thin. Maxillule ( Figure 4 (d)) bilobed with inner lobe (endite) bearing three distal setae; outer lobe (palp) indistinctly 2-segmented, bearing 4 setae with patch of spinules on inner margin. Maxilla ( Figure 4 (e)) 3-segmented, with syncoxa, basis and endopod; syncoxa and basis unarmed; unsegmented endopod forming claw. Maxilliped ( Figure 4 (f)) 5-segmented, comprising syncoxa, basis, and 3-segmented endopod. Syncoxa bearing minute seta; basis bearing row of spinules; endopod bearing proximal segment with seta, middle segment with three setae, and distal segment with seta and slightly, distally curved claw.

Legs 1 to 3 ( Figures 4 (g), 5(a–d)) biramous; leg 4 ( Figure 5 (e,f)) uniramous; both rami bearing 3-segmented rami. Leg armature formula as follows:

Intercoxal sclerites ( Figures 4 (g), 5(b,d,f)) of legs 1 to 4 unarmed. All setae on both rami plumose. Basis of leg 1 bearing row of hairs close to inner seta and inner protrusion. Rami of legs 1 to 4 bearing rows of spinules on outer margins and hairs on both margins. Endopods of legs 1 to 3 ( Figures 4 (g), 5(a,c)) bearing pointed posterolateral processes on middle and distal segments. Leg 5 ( Figure 5 (g)) 2-segmented, protopod fused to pedigerous somite bearing outer seta; exopod rod-like, slightly curved, bearing three setae and row of setules on outer margin. Leg 6 ( Figure 3 (b,c)) represented by three setae on genital operculum.

Variability

The morphology of the male paratype as in the holotype. The measurements of the body parts (n = 1) are as follows: body length 974; cephalothorax length 593; cephalothorax width 665; prosome length 974; genital somite length 162; genital somite width 187; first urosomite length 25; first urosomite width 51; second urosomite length 25; second urosomite width 56; anal somite length 42; anal somite width 57; caudal ramus length 102; caudal ramus width 18. Caudal ramus 5.69 times longer than wide.

Remarks

To date, four species of Entomopsyllus are known. Two species, E. nichollsi McKinnon, 1988 and E. stocki Kim, 2004 , have a single inner seta on the second endopodal segment of leg 2 ( McKinnon 1988; Kim 2004), and another two congeners, E. adriae ( Eiselt, 1959) and E. brevicaudatus Lee and Kim, 2017 , share two setae with E. takara sp. nov. (see Eiselt 1959; Lee and Kim 2017). The new species differs from E. adriae because it shows a shorter sixth segment of the antennule on the male and the third exopodal segment of leg 4 bearing four setae, while E. adriae has the longer sixth segment of the antennule and the third exopodal segment bearing three setae ( Eiselt 1959). The new species clearly differs from E. brevicaudatus by having the following features: leg 2 bearing the third endopodal segment with five setae, and leg 3 bearing the third exopodal segment with three spines and the third endopodal segment with three setae, while E. brevicaudatus has leg 2 bearing four setae and leg 3 bearing four spines and two setae ( Lee and Kim 2017).

Etymology

The specific name of the new species, ‘ takara ’, refers to the name of an island as type locality in Tokara Islands , Kagoshima, Japan .

Newly established Japanese name

‘Kasabuta-kudakuchi-mijinko-ka’ for the family, ‘Kasabuta-kudakuchi-mijinko-zoku’ for the genus, and ‘Kasabuta-kudakuchi-mijinko’ for the species.

Figures

Figure 3. Entomopsyllus takara sp. nov., adult male, NSMT-Cr 25853. (a) habitus, dorsal; (b) urosome, ventral; (c) left leg 6; (d) right caudal ramus, dorsal; (e) right antennule, posterior. Scale bars: (a) 200 μm; (b) 80 μm; (c, e) 20 μm; (d) 50 μm.

Figure 4. Entomopsyllus takara sp. nov., adult male, NSMT-Cr 25853. (a) right antenna, anterior; (b) right mandible, posterior; (c) oral cone; (d) left maxillule, posterior; (e) right maxilla, posterior; (f) left maxilliped, anterior; (g) right leg 1, anterior. Scale bars: (c) 80 μm; (b) 50 μm; (a, d) 40 μm; (e–g) 50 μm.

Figure 5. Entomopsyllus takara sp. nov., adult male, NSMT-Cr 25853. (a) right leg 2, anterior; (b) intercoxal sclerite of leg 2; (c) right leg 3, anterior; (d) intercoxal sclerite of leg 3; (e) right leg 4, anterior; (f) intercoxal sclerite of leg 4; (g) right leg 5, dorsal. Scale bars: (a–f) 50 μm; (g) 40 mm.