Periproctia bisetigera, 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 : 203-206

Periproctia bisetigera sp. nov.

( Figs. 133 , 134 )

Type material. Holotype ♀ (dissected and mounted on a slide, MNHN-IU-2009-5059 ) from Cystodytes sp. (MNHN-IT-2008-2635 = MNHNA3/CYS/135), CRRF DNG 083, marine lake, Raja Ampat, West Papua, Indonesia (00°26.929 Ń, 130°21.149 É), depth 0.5 m, L.J. Bell and L.E. Martin coll., 04 November 2007.

Etymology. The specific name combines the Latin words bi (=two), seta (=bristle), and gero (=carry) and alludes to the presence of 2 setae on the third endopodal segment of the maxilla.

Descriptionoffemale. Body ( Fig. 133A, B ) stout, 1.10 mm long. Prosome cylindrical, 808 μm long. Cephalosome defined from first pedigeroussomite only by dorsal and lateral constrictions: pedigerous somites fused but first pedigerous somite discernible by dorsal and lateral constrictions. No dorsal tergites present on pedigerous somites. Fifth pedigerous somite not defined, fused to fourth. Free urosome narrowing posteriorly, 5- segmented: genitalsomite 45×143 μm, much widerthan long; 4 abdominalsomites 60×110, 65×92, 80×74, and 29×58 μm, respectively.Anal somite ( Fig. 133C ) with pair of highly sclerotized ventral protuberances ornamented with minute spinules around apex. Caudal ramus ( Fig. 133C , 134A ) about 1.6 timeslongerthan wide (31×19 μm), slightlynarrowing distally; armedwith 1 largeand 1 small, stout claws and 4 naked setae; larger claw 33 μm long, longer than ramus and small claw 7 μm long, unnoticeable.

Rostrum small with angular apex, lacking beak-like process at tip. Antennule ( Fig. 133D ) 118 μm long and 8- segmented; armatureformula 2, 13 (or 6, 9), 8+aesthetasc, 3, 2+aesthetasc, 1, 2+aesthetasc, and 7+aesthetasc; setae naked; setaeonproximalsegmentsgenerally long.Antenna ( Fig. 134B ) 4-segmented; coxashortand unarmed; basis also short, widerthan long, bearing 1 extremely long pinnate seta representing exopod at outer distal corner; first endopodal segment slightly longerthan wide, with 1 naked setaon inner margin; compound distal endopodal segment about 2.8 times longer than wide (50×18 μm), ornamented with spinules on mid outer margin; armed with 9 setae (including 1 pinnate and 5 blunt setae) plus terminal claw about half as long as segment.

Labrum missing. Mandible ( Fig. 133E ) with 5 teeth, 1 spinule between distal second and third teeth, and 1 proximal setaon coxal gnathobase; basiswith 1 seta on subdistal medial margin; exopod 2-segmented, with 3 setae on first segment and 2 setae on small second segment; distal seta of second segment about half as long as other 4 setae; endopod incompletely 2-segmented with 2 and 5 setae on first and second segments, respectively; setae on second segment unequal in length. Maxillule ( Fig. 133F ) with 8 setae on arthrite, 1 on coxal endite, 2 on epipodite, 3 on basis, 3 on exopod, and 4 on endopod. Maxilla ( Fig. 133G ) 5-segmented; syncoxawith 9 setae (arranged 3, 1, 2, and 3), 2 on basis, and 1, 1, and 2 on first to third endopodal segments, respectively. Maxilliped ( Fig. 133H ) unsegmented, armedwith 10 setae (8 medial and 2 apical), ornamented with rows of small spinules proximally.

Legs 1–4 ( Fig. 134 C-F) each with 3-segmented exopod and 2-segmented endopod. Inner coxal seta absent in all legs. Outer seta of basis large in leg 1, but small in legs 2 and 4, and minute in leg 3. Inner distal spine on basis of leg 1 as long as first endopodal segment. First and second exopodal segments of legs 2–4 bearing well-developed, dentiform outer distal process. Inner seta absent on first exopodal segment of leg 1 and first endopodal segment of leg 2. Third exopodal segment of legs 2–4 bearing 2 spines distally. Armature formula for legs 1–4 as follows:

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-I	I-0; I-1; II, I, 4	0-0; 1, 2, 2
Leg 2	0-0	1-0	1-1; 1-1; 3, II, 40-0; 1, 2, 5	40-0; 1, 2, 5
Leg 3	0-0	1-0	1-1; 1-1; 2, II, 40-1; 1, 2, 5	40-1; 1, 2, 5
Leg 4	0-0	1-0	1-1; 1-1; 2, II, 40-1; 1, 2, 4	40-1; 1, 2, 4

Leg 5 ( Fig. 134G ) represented by 2 lobes, each lobe tipped with 1 naked seta, both setae equal in length.

Male. Unknown.

Remarks. Two outstanding features characterise the new species: (1) the first exopodal segment of leg 1 lacks an inner seta; and (2) the first endopodal segment of leg 2 also lacks an inner seta. These two features are not known in any of the five described species of Periproctia . The possession of two claws on the caudal ramus which are very unequal in length, may be an additional diagnostic feature allowing for easy recognition of the new species.

Figures

FIGURE 133. Periproctia bisetigera sp. nov., female. A, habitus, right; B, habitus, dorsal; C, anal somite and caudal ramus, right; D, antennule; E, mandible; F, maxillule; G, maxilla; H, maxilliped. Scale bars: A, B, 0.1 mm; C-H, 0.02 mm.

FIGURE 134. Periproctia bisetigera sp. nov., female. A, caudal ramus; B, antenna; C, leg 1; D, leg 2; E, leg 3; F, leg 4; G, leg 5. Scale bars: 0.02 mm.