Lichomolgus forficula Thorell, 1860

Kim, Il-Hoi & Boxshall, Geoff A., 2021, Copepods associated with Ascidian hosts (Tunicata): Intramolgidae and Lichomolgidae, with descriptions of four new genera and 13 new species, Zootaxa 5013 (1), pp. 1-75 : 31-34

publication ID	https://doi.org/ 10.11646/zootaxa.5013.1.1
publication LSID	lsid:zoobank.org:pub:BBB1CB11-1AEA-4678-8F6C-B43B7F35E453
persistent identifier	https://treatment.plazi.org/id/8D4A87BF-FFA5-FFAF-FF19-FDB39886FE68
treatment provided by	Plazi
scientific name	Lichomolgus forficula Thorell, 1860
status

Treatment

( Figs. 19 View FIGURE 19 , 20 View FIGURE 20 )

Material examined. 2 ♀♀ (MNHN-IU-2014-21598) (1 ♀ dissected) in Asc ẚdẚa mentula Müller, 1776, Corsica (42°10.70´N, 09°36.22´E), MEDITS 2016 cruise, RV “L'Europe”, Stn M 16-1, October 2016 GoogleMaps .

Supplementary description of female. Body ( Fig. 19A View FIGURE 19 ) with moderately broad prosome and slender urosome. Body length 1.20 mm; prosome 564×389 μm. Dorsal suture line indistinct between cephalosome and first pediger- ous somite. Urosome ( Fig. 19B View FIGURE 19 ) 5-segmented; fifth pedigerous somite 91 μm wide, narrower than genital double somite. Genital double-somite about 1.5 times longer than wide (158×105 μm), with roundly expanded anterior half and tapering distal half; genital apertures positioned dorsolaterally in middle of double-somite. Three free abdominal somites 48×57, 30×48, and 102×45 μm, respectively; anal somite characteristically elongate (about 2.3 times longer than wide). Caudal ramus ( Fig. 19B View FIGURE 19 ) elongate, about 12.8 times longer than wide (205×16 μm), armed with 6 small, thin setae; lateral seta (seta II) and dorsal seta (seta VII) both positioned at about 37% of ramus length.

Rostrum ( Fig. 19C View FIGURE 19 ) longer than wide, clearly defined from cephalosome, gently tapering towards rounded apex. Antennule ( Fig. 19D View FIGURE 19 ) 214 μm long, 7-segmented; terminal segment shortest; armature formula 4, 13, 6, 3, 4+aesthetasc, 2+aesthetasc, and 7+aesthetasc; 1 of distal setae on second segment distinctly longer than other setae. Antenna ( Fig. 19E View FIGURE 19 ) 4-segmented; armature formula 1, 1, 3, and 4+3 claws; third segment (second endopodal segment) bearing 1 distinct and 2 minute, setule-like setae; terminal segment about 3.1 times longer than wide (55×18 μm); 3 terminal claws extremely unequal in size, 70, 28, and 15 μm long, respectively, smallest hardly visible.

Labrum ( Fig. 19F View FIGURE 19 ) broad and deeply incised; posterior lobes defined from proximal part by surface suture, fringed with narrow membrane along free posterior margin. Mandible ( Fig. 19G View FIGURE 19 ) moderately narrow, with elongate distal lash; ornamented with several rows of spinules on convex outer surface and 1 row of thin spinules along concave inner margin. Maxillule ( Fig. 19H View FIGURE 19 ) lobate, armed with 2 unequal setae on distal margin and 1 small, thin seta on inner margin. Maxilla ( Fig. 19I View FIGURE 19 ) consisting of syncoxa and basis; syncoxa unarmed; basis with 3 unequal setae, inner seta (seta I) large, with 2 rows of spinules along distal margin; distal lash set at right angle to proximal part of basis, ornamented with row of elongate spinules along outer margin. Maxilliped ( Fig. 19J View FIGURE 19 ) 3-segmented; first segment unarmed; second segment tapering and armed with 2 small setae subdistally; third segment small, claw-like, bearing 1 minute seta proximally.

Legs 1-3 ( Fig. 20 View FIGURE 20 A-C) biramous, consisting of coxa, basis, and 3-segmented rami. Inner coxal seta of legs 1-3 pinnate, but that of leg 4 minute and naked. Outer seta on basis of legs 1-4 naked. Third exopodal segment of leg 3 armed with 3 spines and 5 setae, as in leg 4. Leg 4 ( Fig. 20D View FIGURE 20 ) with 3-segmented exopod and 2-segmented endopod; inner seta on proximal endopodal segment about half as long as distal endopodal segment; distal endopodal segment slightly curved, armed with 2 very unequal spines on distal margin, larger inner spine more than 3 times longer than outer, both shorter than segment. Armature formula for legs 1-4 as follows

Coxa Basis Exopod Endopod

Leg 1: 0-1 1-0 I-0; I-1; III, I, 4 0-1; 0-1; I, 1, 4

Leg 2: 0-1 1-0 I-0; I-1; III, I, 5 0-1; 0-2; I, II, 3

Leg 3: 0-1 1-0 I-0; I-1; II, I, 5 0-1; 0-2; I, II, 2

Leg 4: 0-1 1-0 I-0; I-1; II, I, 5 0-1; 0, II, 0

Leg 5 ( Fig. 20E View FIGURE 20 ) consisting of dorsolateral seta on fifth pedigerous somite and free exopod; exopodal segment about 2.6 times longer than wide (28×11 μm), armed distally with 2 unequal, naked setae. Leg 6 ( Fig. 20F View FIGURE 20 ) repre- sented by 2 naked setae and 1 small cusp on genital operculum.

Male. Not found.

Remarks. iẚchomolgus forfẚcula can readily be identified by its characteristic features, including the elongate anal somite and caudal rami, and the presence of the two very unequal terminal claws on the antenna. The third exopodal segment of leg 3 of i. forfẚcula is armed with 3 spines and 5 setae (armature formula II, I, 5). This feature is shared with i. margẚnatus Thorell, 1859 and i. furcẚllatus Thorell, 1859. All three of these species are associated with ascidians and probably represent a distinct genus, but the entire genus is in need of revision.