Notopterophoroides tripartitum, 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 : 182-185

Notopterophoroides tripartitum sp. nov.

( Figs. 119 , 120 )

Type material. Holotype ♀ (dissected and mounted on a slide, MNHN-IU-2014-21255 ) collected along with N. deplanatum sp. nov. from Ascidia ornata Monniot F. & Monniot C., 2001 (MNHN-IT-2008-1160 = MNHN P5/ASC.A/299), CRRFCRCHO 148, Camiguin Island, Bohol Sea, the Philippines (09°15.38 Ń, 124°39.12 É), depth 18 m, 19 April 1997.

Etymology. The specific name tripartitum is derived from the Latin tri (=three) and parti (=a part), referring to the three-segmented prosome.

Descriptionoffemale. Body ( Fig. 119A ) narrow and cylindrical. Bodylength 1.32 mm: prosome 1.06 mm long, occupying 80% of total body length. Prosome 3-segmented, consistingof cephalothorax (227×227 μm) incorporating first pedigerous somite, shorter and narrower than following 2 compound metasomites. First metasomite formed by fusion of second and third pedigerous somites, 410×318 μm. Second metasomite (= fourth and fifth pedigerous somites) 423×290 μm, slightly longer but narrower than first metasomite, with rounded posterodorsal margin. Freeurosome ( Fig. 119B ) small, 5- segmented; genital somite not articulated from metasome, 113 μm wide, narrower than first and second abdominal somites; small copulatory pore present on ventral surface; singlespermatophore ( Fig.119B,D ) attachedtocopulatory pore, 79×29 μm, containing 2 internalchambersof unequal sizes. First abdominal somite 125×139 μm, with convex lateral margins; second and third abdominal somites 103×107 and 58×73 μm, respectively. Anal somite small, 36×55 μm, unornamented, with weak posteroventral protuberance. Caudal rami ( Fig. 119C ) fused with anal somite, divergent, positioned dorsolaterally on somite and widely separated from each other at base, approximately 40×18 μm, with roundly protruded, spinulose apex; armed with 3 naked setae and 3 claws, 25, 16, and 12 μm long.

Rostrum as semicircular anterior protuberance on cephalothorax ( Fig. 119A ). Antennule ( Fig. 119E ) small, 112 μmlong, and 7-segmented; armatureformula 6, 10, 9+aesthetasc, 5, 2+aesthetasc, 3+aesthetasc, and 7+aesthetasc; one setaon second segment spiniform; 2 large setae on first segment pinnate, all other setae naked. Antenna ( Fig.119F )4-segmented, including short, unarmed coxa; basis slightly longer than wide, with 1 large, pinnate outer distal seta representing exopod; first endopodal segment nearly as long as basis, with small setasubdistally on inner side; compound distal endopodal segment about 3.1 times as long as wide (46×15 μm), ornamented with 2 patches of spinules and 1 patch of setules; armed with 9 setae (arranged as 1, 3, 2, and 3) plus strongly curved terminal claw about half as long as segment.

Labrum not observed (fragile, easily destroyed). Mandible ( Fig. 119G ) with 5 teeth, 1 smallseta, and 1 needle-like spinule between second and third distal teeth on coxal gnathobase; basis with 1 seta mediodistally: exopod slender, 2-segmented, armedwith 3 and 2 setae on first and second segments, respectively; outer seta on second segment shorter than other 4 setae: endopod with 4 and 9 setae on first and second segments, respectively. Maxillule ( Fig. 119H ) with 9 setae on arthrite, 1 on coxal endite, 2 on epipodite; 3 on medial margin of basis, 3 onexopodand 4 on endopod. Maxilla ( Fig. 120A ) 5- segmented; syncoxawith 8 setae (3, 1, 2, and 2), 3 on basis, and 1, 1, and 3 on first to third endopodal segments, respectively. Maxilliped ( Fig. 119I ) unsegmented with 7 setae mediodistally and 2 setae apically.

Legs 1–4 ( Fig. 120 B-E) with 3-segmented exopods and 2-segmented endopods; inner seta absent on coxa of all legs; outer seta on basis small and naked. Inner distal spineonbasisofleg 1 naked, curved, 22 μmlong, about 1.5 times longer than first endopodal segment; inner margin of basis setulose. Protopod broad in leg 1, but narrow in legs 2–4. Third exopodal segment of leg 1 armed with seta as first outer element. Endopods of legs 2–4 distinctly shorter than exopods, not extending beyond distal border of second exopodal segment. Inner seta on first endopodal segment of leg 4 vestigial. Armature formula for legs 1–4 as follows:

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-I	I-1; I-1; 1, IV, 2	0-0; 1, 2, 3
Leg 2	0-0	1-0	1-0; 1-0; 2, 1, 4	0-1; 1, 2, 3
Leg 3	0-0	1-0	1-0; 1-0; 2, 1, 4	0-1; 1, 2, 2
Leg 4	0-0	1-0	1-0; 1-0; 2, 1, 3	0-1; 1, 2, 1

Leg 5 ( Fig. 120F ) small, consistingof short protopod and free exopod; protopod with small, naked outer distal seta and several rows of spinules on ventral surface; exopodal segment spindle-shaped, narrow proximally and distally, about 3.1 timeslongerthan wide (23×8 μm) with 2 transverse rows of spinules on both margins plus 1 bifurcate sensilla subdistally, and tipped with 1 naked seta.

Male. Unknown.

Remarks.Thisspeciesisincludedin Notopterophoroides , but with some reservations. It shares with other species of Notopterophoroides the presence of 3 claws on the caudal ramus, 5 setae on the mandibular exopod, plus 4 and 9 setae, respectively, on the first and second endopodal segments of the mandible, and a seta as the proximal outer element on the third exopodal segment of leg 1. However, unlike other species of the genus, it has an unsegmented maxilliped and only 2-segmented endopods in legs 2–4. The 3-segmented prosome, with the first metasomite formed by fusion of the second and third pedigerous somites is, however, particularly distinctive and is a unique characteristic within this group of related genera.

Figures

FIGURE 119. Notopterophoroides tripartitum sp. nov., female.A, habitus, dorsal; B, urosome, ventral; C, anal somite and caudal rami, dorsal; D, spermatophore; E, antennule; F, antenna; G, mandible; H, maxillule; I, maxilliped. Scale bars: A, 0.2 mm; B, 0.1 mm; C-I, 0.02 mm.

FIGURE 120. Notopterophoroides tripartitum sp. nov., female. A, maxilla; B, leg 1; C, leg 2; D, leg 3; E, leg 4; F, leg 5. Scale bars: 0.02 mm.