Periproctiastocki, 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 : 194-197

Periproctiastocki sp. nov.

( Figs. 127 , 128 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21257 ) , paratypes (2 intact ♀♀, MNHN-IU-2014-21258) , anddissectedparatype (♀, figured) from Ritterella tokioka Kott, 1992 (MNHN-IT-2008-7934 = MNHNA 1/ RIT /22), AURACEA 1995, Ibo, Mozambique, depth 0-20 m, Monniot coll., 11 November 1995.

Additionalmaterial. 1 ♀ (dissected)from R. tokioka , Madagascar, (25°25 Ś, 44°15 É), depth 20-27 m, 22 May 2010; 3 ♀♀ (MNHN-IU-2018-1837) and 2 dissected ♀♀ from Eudistoma sp., Bahrain, 20 October 1994.

Etymology. The new species is named in honor of Jan H. Stock who established the genus Periproctia .

Descriptionoffemale. Body ( Fig. 127A ) relatively large, 2.10 mm long, with clearly defined prosomeurosome division. Prosome stout, cylindrical, 0.53 mm in dorso-ventral depth. Cephalosome defined by cephalic shield. First to fourth pedigerous somites fused forming brood pouch, but each defined by their dorsal tergite. Fifth pedigerous somite completely fused to fourth. Free urosome ( Fig. 127B ) graduallynarrowingposteriorly, aboutone-thirdas long as prosome, consistingof distinctly segmented genital and 4 abdominal somites. Genital somite much wider than long (91×220 μm), bearing single copulatory pore on ventral surface. Four abdominal somites wider than long, 125×200, 116×166, 114×139, and 90×103 μm, respectively. First and second abdominal somites ornamented with rows of minute spinules on posteroventral surface. Anal somite ( Fig. 127C ) with highly sclerotized ventral protuberance on each side each ornamented with minute spinules around apex. Anal operculum well-developed ( Fig. 127C ). Caudal ramus ( Fig. 127C ) about 1.3 timeslongerthan wide (46×35 μm), narrowing distally, and armed with 4 claws and 2 setae; lengths of claws 54, 47, 31, and 22 μm, 2 larger claws slightly curved, smaller claws straight, spiniform.

Rostrum ( Fig. 127D ) 94×76 μm, parallel in proximal third and tapering in distal two-thirds, terminating in small, beak-like apical process; ornamented with about 6 pairs of fine setules on ventral surface and small papilla proximally on each side. Antennule ( Fig. 127E ) 148 μm long, and 8-segmented; all segments widerthan long; armatureformula 6, 10, 8+aesthetasc, 3, 2+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; setae crowded, mostly largeand pinnate.Antenna ( Fig. 127F ) stout, 4-segmented; coxa short and unarmed; basis gradually broadening distally, with large, plumose seta representing exopod at outer distal corner; first endopodal segment slightly longer than wide, with 1 inner subdistal seta; compound distal endopodal segment about 2.8 times longerthan wide (77×28 μm), ornamented with 3 patches of minute spinules on both outer and inner sides; armed with 9 setae (4 distal setae blunt at tip) plus small terminal claw, about one-thirdaslongas segment.

Labrum ( Fig. 127G ) with setulose posteromedian lobe and setules on posterior margin. Mandible ( Fig. 127H ) with 5 teeth and 1 setaon coxalgnathobase and 1 or 2 needle-like spinules between distal second and third teeth; basis with 1 seta onsubdistal medial margin; exopod 2-segmented and armed with 3 setae on first segment and 2 on small second segment), distalmost seta small (about half as long as other setae), ornamented with setules on medial margin of first segment: endopod 2-segmented but articulation between segments indistinct: armed with 2 and 6 setae on first and second segments, respectively, 2 mid-terminal setae (third and fourth setae) on second segment much larger than other 4 setae. Maxillule ( Fig. 127I ) armed with 9 setaeon arthrite, 1 on coxal endite, 2 on epipodite, 3 onmedial margin of basis, 3 on exopod, and 4 on endopod. Maxilla ( Fig. 128A ) 5-segmented; syncoxa with 3, 1, 2, and 4 setae on first to fourth endites, respectively, basiswith 2 setae, and with 1, 1, and 3 setae on first to third endopodal segments, respectively. Maxilliped ( Fig. 128B ) unsegmented with 10 setae (8 medial and 2 apical).

Legs 1–4 ( Fig. 128 C-F) each with 3-segmented exopod and 2-segmented endopod; second segment of leg 3 endopod subdivided by incomplete suture line on outer side. All legs lacking inner coxal seta. Outer seta on basis very large, about 3 times aslongas exopodin leg 1 butsmall and naked in legs 2–4. Three distal setae on endopod of leg 1 enlarged. Ventral surface of coxa of legs 2–4 with long setules on outer side. First and second exopodal segments of legs 2–4 with bifurcate or trifurcate outer distal corner. Third exopodal segment of legs 3 and 4 elongate. Outer and distal setae on exopods of legs 2–4 naked and blunt tipped. 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	0-1; 1, 2, 4

Leg 5 ( Fig. 127B ) small, consisting of protopod and free exopod. Protopod extended posterolaterally, bearing apical seta; exopodal segment very smallwith small apical seta.

Male. Unknown.

Remarks. The genus Periproctia is currently regarded as containing three valid species, P. biuncata , P. falsiarcuata , and P. triuncata Stock, 1967 , all described when the genus was established ( Stock, 1967). The new species differs from these three species in having: (1) 4 claws and 2 setaeon the caudal ramus (in contrast to 2 claws and 4 setae in P. biuncata , and 3 claws and 3 setae in the other two species), (2) 6 setae on the second endopodal segment of the mandible (vs. 5 setae in all 3 congeneric species), (3) an inner seta on the second exopodal segment of leg 4 (vs. seta absent in congeners), and (4) 8 setae on the endopod of leg 4 (compared to 4 setae in P. biuncata and 6 setae in the other two species).

The additional specimens extracted from Eudistoma sp. collected from Bahrain have a body length of 1.16-1.25 mm, which is significantly smaller than the type specimens. Nevertheless, there were no other morphological differences between the samples, so we tentatively identify them as Periproctia stocki sp. nov.

Figures

FIGURE 127. Periproctia stocki sp. nov., female. A, habitus, right; B, urosome, ventral; C, anal somite and caudal ramus, right; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandible; I, maxillule. Scale bars: A, 0.2 mm; B, 0.1 mm; C-G, I, 0.02 mm; H, 0.05 mm.

FIGURE 128. Periproctia stocki sp. nov., female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, exopod of leg 3; F, leg 4. Scale bars: A, B, 0.02 mm; C-F, 0.05 mm.