Asterocheres tetraodontis, Lee, 2024

Lee, Il-Hoi Kim and Taekjun, 2024, Copepods of the genus Asterocheres Boeck, 1859 (Siphonostomatoida: Asterocheridae) from Korean waters, Journal of Species Research 13 (2), pp. 185-254 : 237-240

publication ID	https://doi.org/ 10.12651/JSR.2024.13.2.185
persistent identifier	https://treatment.plazi.org/id/ED1887CB-FFCA-FFDC-FF7F-B07DB15067F3
treatment provided by	Felipe
scientific name	Asterocheres tetraodontis
status	sp. nov.

Treatment

Asterocheres tetraodontis n. sp. ( Figs. 33 View Fig , 34 View Fig )

https://zoobank.org/urn:lsid:zoobank.org:act:337B5104-

1AD3-443C-8AD3-2404EF566717

Type material. Holotype (♀; NIBRIV0000909867 ) , Paratypes (3♀♀; NIBRIV0000909868 ), and dissected paratype (1♀) from mixed species of sponges, Ulleung Island (approximately 37°32 ʹ 25 ʺ N, 130°50 ʹ 50 ʺ E), depth about 20 m, SCUBA diving, coll. J. Lee, 29 August 2018 GoogleMaps . Holotype and intact paratypes have been deposited in the National Institute of Biological Resources ( NIBR), Incheon, Korea. Dissected paratype is retained in the collection of I.-H. Kim .

Etymology. The name tetraodontis (from Greeks, tetra meaning “four” and odon meaning “a tooth”) refers to the four distal teeth of the mandibular stylet.

Female. Body ( Fig. 33A View Fig ) moderately broad. Body length of figured and described specimen 796 μm. Prosome 513 × 422 μm. Cephalothorax 353 μm long, wider than long. All prosomal somites with rounded posterolateral corners. Urosome ( Fig. 33B View Fig ) 4-segmented. Fifth pedigerous somite wider than genital double-somite, with 1 or 2 spinules on lateral margin. Genital double-somite as long as wide (117 × 118 μm), widest at proximal third, gradually narrowing posteriorly from widest region; genital apertures positioned laterally at 45% region of double-somite length; postgenital lateral margin bearing 2 groups of spinules, anterior group consisting of 4 or 5 shorter spinules and posterior group of 4 longer spinules ( Fig. 34F View Fig ); posterior region of lateral margin with 2 scales. Two free abdominal somites 48 × 70 and 36 × 64 μm, respectively. Anal somite with spinules of irregular sizes along posteroventral margin ( Fig. 33C View Fig ). Caudal ramus ( Fig. 33C View Fig ) as long as wide (27 × 27 μm), bearing longer outer margin and shorter inner margin, armed with 6 setae, and ornamented with spinules along posteroventral margin.

Rostrum ( Fig. 33D View Fig ) represented by ridge bearing concave lateral margins, without posterior apex. Antennule ( Fig. 33E View Fig ) 337 μm long, 20-segmented; 9th, 18th, and terminal segments with 7 setae, 2 setae + aesthetasc, and 9 setae, respectively; all other segments each with 2 setae; several setae on proximal segments pinnate; all setae attenuated, not truncated at tip. Antenna ( Fig. 33F View Fig ) comprising coxa, basis, small exopod, and 3-segmented endopod; coxa short, unarmed; basis unarmed but ornamented with fine spinules near exopod; exopod 9 × 5.5 μm, bearing 1 proximal and 2 distal setae; first endopodal segment 57 μm long, unarmed but ornamented with setules along outer margin; small second endopodal segment with 1 seta; third endopodal segment with 2 setae; terminal claw spiniform, 52 μm long.

Oral siphon ( Fig. 33G View Fig ) rather stout, 147 × 57 μm, reaching maxilliped insertions, constricted near proximal quarter. Mandible ( Fig. 33H View Fig ) consisting of coxal stylet and palp; stylet 133 μm long, bearing 4 teeth distally including hook-like terminal tooth; palp 1-segmented, 46 μm long, tipped with 2 unequal, weakly pinnate setae, longer seta 118 μm long, and shorter seta 47 μm long; palp plus longer distal seta 164 μm long, 1.23 times longer than stylet. Maxillule ( Fig. 33I View Fig ) bilobed; inner lobe about 67 μm long, tipped with 1 rudimentary and 4 distinct setae (lengths 69, 70, 65, and 37 μm, respectively, from inner to outer); outer lobe 18 μm long, tipped with 4 setae (lengths 59, 55, 50, and 18 μm, respectively). Maxilla ( Fig. 33J View Fig ) 2-segmented; both segments smooth, lacking spinules or setules; distal segment slender, distinctly longer than proximal segment. Maxilliped ( Fig. 33K View Fig ) 6-segmented; armature formula 1, 0, 2, 1, 1, and 1 + claw; terminal segment and claw 36 and 58 μm long, respectively.

Legs 1 ( Fig. 34A View Fig ), 2 ( Fig. 34B View Fig ), 3, and 4 ( Fig. 34D View Fig ) segmented and armed as in general for genus. Leg 3 similar to leg 2, but with 1 spine and 5 setae on the third endopodal segment ( Fig. 34C View Fig ). Inner coxal seta pinnate in legs 1-3 but small, naked in leg 4. Intercoxal plate bearing spinules in leg 1, but smooth in legs 2-4. Outer seta on basis of leg 1 subequal in length to that of leg 2. Mediodistal margin of basis of leg 1 bearing spinules. Inner distal seta on basis of leg 1 thin, bearing few setules on proximal part of outer margin. Outer distal process of first endopodal segment of legs 3 and 4 larger than those of legs 1 and 2. Outer distal corner of second endopodal segment of legs 1-4 with bicuspid process. Armature formula for legs 1-4 as in A. aesthetes .

Leg 5 ( Fig. 33B View Fig ) consisting of dorsolateral seta on fifth pedigerous somite and exopod; exopodal segment ( Fig. 34E View Fig ) rectangular, 2.50 times longer than wide (55 × 22 μm), armed with 3 setae and ornamented with several scales on inner and outer margins; lengths of setae 51, 62, and 32 μm, respectively, from outer to inner; first and second outer setae pinnate, but innermost seta naked, with proximal annulation. Leg 6 ( Fig. 34F View Fig ) represented on genital operculum by 1 small, naked seta tipped on digitiform process and 1 spinule.

Male. Unknown.

Remarks. Asterocheres tetraodontis n. sp. shows relatively high similarity values (more than 75%) with five congeners: A. indivisus Kim, 2010 ; A. planus Kim, 2010 ; A. spinosus Kim & Min, 2013 ; A. eurychelatus n. sp.; and A. scutellatus n. sp. It is noticed that the latter five species have in common a 20-segmented female antennule bearing an aesthetasc on the 18th segment and a 1-segmented mandibular palp which is longer than the stylet. However, these five congeners differ from A. tetraodontis n. sp. in having the following different features in the female:

In A. indivisus , the caudal rami and genital double-somite are distinctly wider than long (vs. as long as wide in A. tetraodontis n. sp.), and the exopodal segment of leg 5 is fusiform (vs. rectangular in A. tetraodontis n. sp.) and its outer and middle distal setae are characteristically long, more than twice longer than the segment (vs. the setae are not so long in A. tetraodontis n. sp.). In A. planus , the caudal ramus is distinctly longer than wide, the mid-terminal seta on the exopod of leg 5 is longer than the other two setae, the cephalothorax is broadened, and the distal segment of the maxilla is stout and strongly curved. In A. spinosus , the caudal ramus is 1.88 times longer than wide, the postgenital lateral margin of the genital double-somite is ornamented with numerous setules, and the oral siphon extends over the maxilliped ( Kim & Min, 2013). In A. eurychelatus n. sp., the genital double-somite is distinctly longer than wide, the terminal claw of the antenna and maxilliped is broadened, and the exopodal segment of leg 5 is fusiform, with three subequal naked setae. In A. scutellatus n. sp., the genital double-somite is distinctly longer than wide, the mandibular stylet bears six teeth distally (vs. four teeth in A. tetraodontis n. sp.), the exopodal segment of leg 5 is slightly fusiform and its distal setae are all naked and shorter than the exopodal segment (vs. the exopodal segment is rectangular and two of distal setae pinnate and the mid-terminal one is longer than the segment in A. tetraodontis n. sp.).