Lonchidiopsis replicata, 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 : 451-454

Lonchidiopsis replicata sp. nov.

( Figs. 299 , 300 )

Type material. Holotype ♀ (dissected and mounted on a slide, MNHN-IU-2014-21358 ) from Plurella kottae Monniot F. & Monniot C., 1996 (Holotype MNHN-IT-2008-6248 = MNHN P7/PLU.A/1), CRRFOCDN 2088-F, Buyong, Mactan Island, Cebu, the Philippines (10°17.19’N, 124°00.15’E), depth 27 m, 07 February 1994.

Etymology. The specific name is derived from the Latin replic (=fold back), referring to the shape of the brood pouch.

Descriptionoffemale. Body ( Fig. 299A ) highly transformed, laterally compressed, consisting of cephalothorax, short neck, greatly expanded brood pouch, and 4-segmented freeurosome. Bodylength 1.70 mm. Cephalic shield expanded ventrolaterally, concealing part of surface extending from mouthparts to third pedigerous somite in lateral view. Short neck region without appendages. Fourth pedigerous somite forming brood pouch, extremely compressed but expanded in vertical planeto form paireddiscoid lateralfolds separatedby deep dorsal furrow. Freeurosome ( Fig. 299B ) 4-segmented, consisting of genital double-somite and 3-segmented abdomen, Caudal rami fused to anal somite without any trace of articulation, slightly longer than wide; armed with 6 minute setae on convex distal margin ( Fig. 299C ).

Rostrum ( Fig. 299D ) small, 20×22 μm, highly sclerotized with rounded apex. Antennule ( Fig. 299F ) about120 μmlong, 6-segmented; firstandsecondsegments extremely expanded; third segment inserting into middle of secondsegment; armatureformula 2, 14, 3, 2, 2, and 13. Antenna ( Fig. 299G ) 3-segmented, consistingof coxa, allobasis, and 1-segmented endopod; allobasis 57×23 μm, unarmed, with unsclerotized area near middle as trace of articulation; freeendopodal segment 32×15 μm, armed with 2 setae in middle of inner margin, and ornamented with 4 or 5 spinules on distal outer margin; terminal claw about 19 μm long, attenuated at tip.

Labrum ( Fig. 299E ) with large, linguiform posteromedian lobe and setulose posterior margin. Mandible ( Fig. 299H ) with broad coxalgnathobase bearing 5 teeth on medial margin and 1 setaon proximal margin: basis with seta at mediodistal corner: exopod with 5 large setae, medial seta pinnate proximally but with spinulesalongdistalpartof medial margin; firstendopodal segment almost fused to basis, with trace of articulation on medial side, armed with 4 setae, distalmost seta broad and pinnate, with long setules; second endopodal segment armedwith 9 setae, 5 medial setae spinulose along distal half of medial margin. Maxillule ( Fig. 299I ) with 10 setae on arthrite; coxa with 1 setaon endite and 2 very unequal setae on epipodite; basis with 4 setae (second and fourth setae shorter than first and third); exopod with 4 setae on distal margin; endopod with 2 medial and 3 distal setae (second medial seta broad, curved outwards, with thick setules along convex margin; outermost distal seta longest). Maxilla ( Fig. 300A ) 4-segmented; syncoxawith 4, 1, 2, and 3 setae on first to fourth endites, respectively; basis with large claw bearing serrations along distal half of convex margin plus 2 unequal setae; endopod atrophied, 2-segmented, first segment unarmed, second with 5 small setae. Maxilliped ( Fig. 300B ) distinctly 2-segmented; first segment with 6 setaeon medial margin; secondsegment narrow with 3 setae.

Legs 1–3 biramous with 2-segmented rami ( Fig. 300C, D ); innercoxalsetaabsent; outersetaonbasis large inleg 1, butsmall in legs 2 and 3. Inner margin of basis and outer margin of endopod setulose in leg 1, but smooth in legs 2 and 3. Compound second endopodal segment of leg 1 ovate with spinulose margins. Leg 4 absent. Armature formula for legs 1–3 as follows:

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-1	I-1; I-0; II, I, I	0-1; 1, 2, 2
Leg 2	0-0	1-0	1-1; 1-0; 2, II, 10-1; II, I, I+1	10-1; II, I, I+1
Leg 3	0-0	1-0	1-0; 0-0; 1, 1, 2	0-1; 1, 2, 1
Leg 4	0-0	1-0	1-0; 0-0; 0, 3, 0	0-0; 0, 2, 0

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-I	I-1; II, I, I	0-1; 1, 2, I+1
Legs 2 & 3	0-0	1-0	I-1; I, I, I	0-0; I, II, II

Leg 5 ( Fig. 300E ) represented by small free exopodal segment about 3.6 times longer than wide (101×28 μm), with narrow proximal third and broader distal two-thirds; armed with 2 unequal setae distally.

Male. Unknown.

Remarks. Despite the highly transformed body form which makes L. replicata sp. nov. instantly recognizable, its cephalic appendages and legs share various similarities with those of its three congeners. The unique features of the new species within the genus include; the caudal rami are completely fused to the anal somite (vs. the caudal rami are free in all congeneric species), the distal endopodal segment of leg 1 is armed with 1 spine and 4 setae (vs. 1 spineand 5 setaein congeners), and leg 4 is absent (vs. this leg is present in congeners, although it is rudimentary in L. setosus and L. tripes ).

Figures

FIGURE 299. Lochidiopsis replicata sp. nov., female.A, habitus, left; B, urosome, right; C, posterior part of urosome, dorsal view showing rami fused to anal somite, with inset showing detail of caudal setae; D, rostrum; E, labrum; F, antennule; G, antenna; H, mandible; I, maxillule. Scale bars: A, 0.2 mm; B, C, 0.1 mm; D, 0.01 mm; E–I, 0.02 mm.

FIGURE 300. Lochidiopsis replicata sp. nov., female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, leg 5. Scale bars: A–D, 0.02 mm; E, 0.05 mm.