Periproctia obtusispinata, 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 : 235-236

Periproctia obtusispinata sp. nov.

( Figs. 155 , 156 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21277 ) , paratypes (3 intact ♀♀, MNHN-IU-2014-21278), and dissected paratypes (3 ♀♀, figured) from Lissoclinum timorense (Sluiter, 1909) . Each copepod was removed from a membranous cyst, Mont Dore, New Caledonia, Monniot coll.

Additionalmaterial. 8 ♀♀ (MNHN-IU-2018-1838) from L. timorense, Mont Dore , New Caledonia.

Etymology. The specific name combines the Latin words obtus (=blunt) and spina (=spine), alluding to the blunt claws on the caudal ramus.

Descriptionoffemale. Body ( Fig. 155A ) stout, 830 μm long. Prosome 700 μm long, occupying 84% of body length, with thin, soft exoskeleton. Dorsoventral depth of prosome 335 μm.Cephalosome fusedwithfirstpedigerous somite, but defined by lateral expansions of cephalic shield with small spiniform process at each posterolateral corner ( Fig. 155B ). First to fourth pedigerous somites fused, forming entirebrood pouch: fifth pedigerous somite completely fused with fourth. Free urosome ( Fig. 155C ) steeply tapering, 5-segmented: genitalsomite 36×120 μm; 4 abdominalsomites 45×93, 33×73, 36×53, and 27×34 μm, respectively. First to third abdominal somites each ornamented with 1 or 2 transverse rows of minute spinules ventrally. Anal somite ( Fig. 155C, D ) bluntly protruded posteroventrally to form convex posteroventral margin, unornamented. Caudalramus small, about 1.25 times longerthan wide (15×12 μm): armedwith 3 blunt claws and 3 setae; lengths of claws 16, 11, and 9 μm; setae naked, not longerthan ramus.

Rostrum ( Fig. 155E ) weak, muchwiderthanlong, 36×76 μm, with rounded distal margin lacking any processes. Antennule ( Fig. 155F ) 88 μm long and 6- segmented; armatureformula 6, 9, 6+aesthetasc, 3, 2+aesthetasc, and 11+2 aesthetascs; terminal segment subdivided into 3 parts by 2 partial suture lines on one surface; all setae naked and relatively short.Antenna ( Fig. 155G ) stout, 4-segmented; coxashortand unarmed; basis wider than long and unarmed (lacking exopodal seta); first endopodal segment slightly longer than wide, with 1 seta on inner margin; compound distal endopodal segment about 2.3 times longer than wide (30×13 μm); armed with 7 setae (3 distal setae blunt at tip) plus terminal claw about half aslongas segment.

Labrum very weak, missing. Mandible ( Fig. 155H ) bearing several denticles of irregular sizes on coxal gnathobase; basis elongate with 1 seta on medial margin; exopod 2-segmented, armedwith 3 and 2 setaeonfirst and second segments, respectively; outer distal seta on second exopodal segment slightly shorter than other 4 setae; endopod with 2 and 5 setae on first and second segments, respectively. Maxillule ( Fig. 155I ) with 5 setae on arthrite; coxa with only 1 seta on epipodite, lacking endite; basiswith 2 setaeon medial margin; exopod and endopodwith 3 and 4 setae, respectively. Maxilla ( Fig. 155J ) 5-segmented and armed with 3, 2, and 2 setae respectively on first to third endites of syncoxa, 2 setae on basis, and 1, 1, and 3 setae on first to third endopodal segments, respectively. Maxilliped ( Fig. 156A, B ) armed with 2-4 medial setae and 1 outer distal seta; number of medial setae variable, 4, 4, 4, 3, 2, and 2 setae respectively on observed maxillipeds of 3 dissected specimens (4 setae is considered to be normal condition).

Legs 1–4 ( Fig. 156 C-F) with 3-segmented exopods and 2-segmented endopods. Outer seta on basis large in leg 1, but small in legs 2–4. Inner distal spine on basis of leg 1 as long as first endopodal segment, 12 μm long. Outer setae on exopods of legs 2–4 small. Inner seta on second exopodal segment of leg 4 small. Second endopodal segment of leg 4 armed only with 4 setae. Armature formula for legs 1–4 as follows:

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-I	I-1; I-1; II, I, 4	0-0; 1, 2, 3
Leg 2	0-0	1-0	1-1; 1-1; 3, 1, 5	0-1; 1, 2, 5
Leg 3	0-0	1-0	1-1; 1-1; 2, 1, 5	0-1; 1, 2, 5
Leg 4	0-0	1-0	1-1; 1-1; 2, 1, 5	0-0; 1, 2, 1

Leg 5 ( Fig. 156G ) small, consisting of free protopod and exopod; protopodal segment extended distally, forming digitiform process bearing naked seta at tip; exopod clearly articulated at base, tapering, armed with naked apical seta.

Male. Unknown.

Remarks. Periproctia obtusispinata sp. nov. and P. biuncata are the only two species lacking the outer distal seta representing the exopod on the basis of the antenna. Moreover, they also have in common a 6-segmented antennule, and the presence of only 2 setae on the basis of the maxillule and only 4 setae on the endopod of leg 4. Nevertheless, they differ in numerous other character states ( Table 3) including: P. obtusispinata sp. nov. has 3 setae (vs. 2 setae in P. biuncata ) on the third endopodal segment of the maxillule, at most 5 setae (vs. 7 setae in P. biuncata ) on the maxilliped, an inner seta on the second exopodal segment of leg 1 (vs. absent in P. biuncata ), 6 setae on the second endopodal segment of leg 1 (vs. 5 setae in P. biuncata ), and an inner seta on the first and second exopodal segments of leg 4 (vs. absent in P. biuncata ). These differences are sufficient to justify the establishment of the new species.

Figures

FIGURE 155. Periproctia obtusispinata sp. nov., female. A, habitus, right; B, posterolateral process of cephalosome; C, urosome, ventral; D, anal somite and caudal ramus, right; E, rostrum; F, antennule; G, antenna; H, mandible; I, maxillule; J, maxilla. Scale bars: A, 0.1 mm; B, I, 0.01 mm; C, 0.05 mm; D-H, J, 0.02 mm.

FIGURE 156. Periproctia obtusispinata sp. nov., female. A, B, maxillipeds; C, leg 1; D, leg 2; E, exopod of leg 3; F, leg 4; G, leg 5. Scale bars: A, B, G, 0.01 mm; C-F, 0.02 mm.