Gunenotophorus antennularis, Kim & Boxshall, 2020

Kim, Il-Hoi & Boxshall, Geoff A., 2020, Untold diversity: the astonishing species richness of the Notodelphyidae (Copepoda: Cyclopoida), a family of symbiotic copepods associated with ascidians (Tunicata), Megataxa 4 (1), pp. 1-6 : 151-154

Gunenotophorus antennularis sp. nov.

( Figs. 99 , 100 )

Type material. Holotype ♀ (dissected and mounted on a slide, MNHN-IU-2014-21246 ) from Molgula amesophleba (Codreanu & Mack-Fira, 1956) , Etang de Leucate , Mediterranean coast of France, Clanzig coll., 1985.

Etymology: The name of the new species alludes to the unique lobate form of the paired antennules of the female.

Description of female. Body ( Fig. 99A ) form very similartothatof G. globularis , but larger; bodylength 7.05 mm. Urosome ( Fig. 99B ) 5-segmented, but articulations indistinct between fifth pedigerous and first abdominal somites. Fifth pedigerous and genital somites short, about equal in length. Anal somite longer than wide, with trace of suture line near middle of dorsal surface; ornamented with covering of minute spinules on ventral and dorsal surfaces. Caudal rami directed laterally ( Fig. 99B ), obscurely defined from anal somite; each ramus ( Fig. 99C ) tapering, slightly curved, about 1.3 timeslongerthan wide (313×247 μm); caudal setae minute, hardly visible.

Rostrum ( Fig. 99D ) linguiform, tapering, rounded distally, and ornamented with dense convering of setules on all surfaces. Antennule ( Fig. 99E ) simple, lobate, unsegmented and unarmed, rounded distally, only narrowing slightly towards tip, 193×143 μm, traces of articulations visible in proximal third; distal two-thirds ornamented with dense covering of setules. Antenna ( Fig. 99F ) stout, 4-segmented, as in female G. globularis .

Labrum ( Fig. 99G ) tapering strongly; posterior part forming large, setulose lobe. Mandible ( Fig. 99I ) with broad medial margin on coxal gnathobase bearing 6 teeth and 1 small seta; basis with 1 seta on distal medial margin; exopod indistinctly 2-segmented and armed with 2 and 3 setae on first and second segments, respectively, outer seta on second segment short and broad; endopod 2-segmented with 1 and 4 setae on first and second segments, respectively, 2 medial setae on second segment shorter than distal setae, with swollen basal region. Paragnath ( Fig. 99H ) with 2 large dentiform processes apically and dense covering of setules on medial surface. Maxillule ( Fig. 99J ) as in G. globularis , but all 9 setae on arthrite prominent. Maxilla ( Fig. 99K ) similartothatof G. globularis , except endopod bearing 4 setae (2 shorter and 2 longer). Maxilliped ( Fig. 100A ) unsegmented, armed with 7 setae and ornamented with 3 patches of minute spinules on outer surface.

Legs 1 and 2 ( Fig. 100B, C ) with 3-segmented rami. Legs 3 and 4 ( Fig. 100E, F ) with 3-segmented exopods and 2-segmented endopods. Innercoxalsetaabsentinlegs 1–4. Leg 1 outer setaon basis with thickened, sinuous proximal part; inner distal spine of basis broad and pinnate; exopod broad and distinctly longer than endopod. Exopod twice as long as endopod in leg 2, 3.3 times longer in leg 3, and 2.6 times longer in leg 4. Endopod ( Fig. 100D ) of leg 2 ornamented with 4 rings of setules, 1 on second and 3 on third segments. Similar but less prominent setular rings present on distal endopodal segment of legs 3 and 4, 1 on leg 3 and 2 on leg 4. All setae on legs 2–4 rudimentary. Armature formula for legs 1–4 as follows:

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-0/I	I-1; I-1; VI, 1	0-0; 1, 2, 2 or 0-0;0-1;1,2,1
Leg 2	0-0	1-0	I-1; I-1; VI, 2	0-1; 0-0; 1, I, 3 or 1,II,2 or I,2
Leg 3	0-0	1-0	I-0; I-1; V, 2	0-1; 0-0; 1, I, 3 or 1,II,2 or I,2
Leg 4	0-0	0/1-0	I-0; I-1; V, 2	0-0; 0-0; 1, I, 2 or 1,II,1 or I,2

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-I	I-1; I-1; III, 4	0-1; 0-1; 2, 2, 2
Leg 2	0-0	1-0	1-0; 1-0; 3(or 4)	0-0; 0-0; 1, 3, 1
Leg 3	0-0	1-0	1-0; 1-0; 3(or 4)	0-0; 1, 3, 1
Leg 4	0-0	1-0	0-0; 0-0; 4	0-0; 1, 5, 1
Leg 5	absent.

Male. Unknown.

Remarks. In all previously described species of Gunenotophorus the antennule is segmented and strongly tapering. In contrast, the female of this distinctive new species has lobate, unsegmented antennules that are densely ornamented with setules and apparently lack any typical setation elements. The new species is very similar to G. globularis in external body form. In addition to the antennule, the new species differs in having 4 setae (vs. 5 in G. globularis ) on the second endopodal segment of the mandible.

Figures

FIGURE 99. Gunenotophorus antennularis sp. nov., female. A, habitus, right; B, urosome, ventral; C, right caudal ramus, dorsal; D, rostrum; E, antennule; F, antenna; G, labrum; H, paragnath; I, mandible; J, maxillule; K, maxilla. Scale bars: A, 1 mm; B, 0.5 mm; C, D, 0.1 mm; E–K, 0.05 mm.

FIGURE 100. Gunenotophorus antennularis sp. nov., female. A, maxilliped; B, leg 1; C, leg 2; D, endopod of leg 2; E, leg 3; F, leg 4. Scale bars: 0.1 mm.