Untold diversity: the astonishing species richness of the Notodelphyidae (Copepoda: Cyclopoida), a family of symbiotic copepods associated with ascidians (Tunicata) Author Kim, Il-Hoi 0000-0002-7332-0043 Korea Institute of Coastal Ecology, Inc., 802 - ho, 302 - dong, 397 Seokcheon-ro, Ojeong-gu, Bucheon, Gyeonggi-do 14449, Republic of Korea ® ihkim @ gwnu. ac. kr; https: // orcid. org / 0000 - 0002 - 7332 - 0043 ihkim@gwnu.ac.kr Author Boxshall, Geoff A. 0000-0002-7332-0043 Korea Institute of Coastal Ecology, Inc., 802 - ho, 302 - dong, 397 Seokcheon-ro, Ojeong-gu, Bucheon, Gyeonggi-do 14449, Republic of Korea ® ihkim @ gwnu. ac. kr; https: // orcid. org / 0000 - 0002 - 7332 - 0043 ihkim@gwnu.ac.kr text Megataxa 2020 2020-12-24 4 1 1 6 http://zoobank.org/3fdd970e-62f1-4f67-8cce-10870bdb3c01 journal article 54097 10.11646/megataxa.4.1.1 7c9bc39d-9910-46f1-9558-c0647b9cbbdb 2703-3090 4591138 Periproctia hexachaetata sp. nov. ( Figs. 151 , 152 ) Typematerial . Holotype (intact ♀ , MNHN-IU-2014- 21274 ) anddissectedparatype ( ♀ , figured) from Lissoclinumpatella (Gottschaldt, 1898) (MNHN-IT-2008- 5014 = MNHNA 2/ LIS /157), CRRFOCDN 5762-W, Boia Boia Waga Island, Papua New Guinea ( 10°12.26’S , 150°44.75’E ), depth 10 m , 27 May 1998 . Etymology . The specific name is from the Greek hexa (=six) and chaet (=a bristle), alluding to the presence of 6 setae on the maxilliped. Descriptionoffemale . Body ( Fig. 151A ) slender, cylindrical, 925 μm long; prosome 727 μmlong and 200 μm in dorsoventral depth. Four pedigerous somites fused butdiscernibleby retaineddorsal tergitesand constrictions between them: fifth pedigerous somite completely fused with fourth. Freeurosome ( Fig. 151B ) 5-segmented, with nearly parallel lateral margins; genital somite 108 μm wide, onlyslightly widerthan first abdominal somite. Four abdominalsomites 59×88, 53×82, 64×77, and 30×62 μm, respectively; first to third abdominal somites ornamented with 2 rows of minute spinules ventrally. Anal somite with pair of smooth ventral protuberances. Caudal rami widely separated from each other at base and directed posterolaterally; each ramus ( Fig. 151C ) subrectangular, about 1.3 times longer than wide (24×19 μm); armed with 3 claws and 3 naked setae; lengths of claws 24, 17, and 12 μm; smallest dorsal claw thin. FIGURE 151. Periproctia hexachaetata sp. nov. , female. A, habitus, right; B, urosome, ventral; C, caudal ramus; D, antennule; E, antenna; F, mandible; G, maxillule; H, maxilla; I, maxilliped. Scale bars: A, 0.1 mm; B, 0.05 mm; C-I, 0.02 mm. FIGURE 152. Periproctia hexachaetata sp. nov. , female. A, leg 1; B, leg 2; C, leg 4. Scale bars: 0.02 mm. Rostrum similar to that of P . obtusa sp. nov . , as long as wide (54×54 μm), with small beak-like process at apex. Antennule ( Fig. 151D ) 94 μm long and 7-segmented; armatureformula 5, 13+aesthetasc, 3, 2+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; 4 setae on each of first and second segments pinnate. Antenna ( Fig. 151E ) 4- segmented; coxashortand unarmed; basis short, wider than long, with large outer distal seta representing exopod; first endopodal segment with 1 seta on inner margin; compound distal endopodal segment about 2.9 times longer than wide (47×16 μm), ornamented with spinules on outer margin; armed with 6 setae (grouped as 1, 2, and 3) plus slender terminal claw, about half as long as segment, Labrum missing. Mandible ( Fig. 151F ) with 5 teeth, 2 needle-like spinules between second and third teeth, and 1 smallsetaoncoxalgnathobase; basiswith 1 medial seta; exopod with 5 setae, distal outer seta shorter than other 4; endopod with 2 and 5 setae on first and second segments, respectively. Maxillule ( Fig. 151G ) with 7 setae on arthrite, 1 on coxal endite, 2 on epipodite, 3 on each basis and exopod, and 4 on endopod. Maxilla ( Fig. 151H ) with 9 setaeonsyncoxa (grouped as 3, 1, 2, and 3), 2 on basis, and 1, 1, and 2 setae on first to third endopodal segments, respectively. Maxilliped ( Fig. 151I ) armedwith 5 (2+3) medial setae and 1 apical seta. Legs 1–4 each with 3-segmented exopod and 2- segmented endopod ( Fig. 152 A-C). Outer seta on basis of leg 1 large, as typical for genus. Inner setae on exopod and second endopodal segment of leg 1 small. Inner seta absent on second exopodal segment of legs 3 and 4. First and second exopodal segments of legs 2–4 with strong dentiform outer distal process. Inner seta on first exopodal segment of legs 2 and 3 very large, more than twice as long as exopod. 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; 1-0; 2, 1, 5 0-0; 1, 2, 5
Leg 4 0-0 1-0 1-1; 1-0; 2, 1, 5 0-0; 1, 2, 4
Leg 5 ( Fig. 151B ) small, consisting of small outer distal extension on posteroventral margin of somite, tipped with naked seta, and tiny free exopod with naked apical seta. Male . Unknown. Remarks . The most characteristic feature of P. hexachaetata sp. nov . is the possession of only 6 setae (5 medial and 1 apical) on the maxilliped. This armature pattern of the maxilliped has not previously been recorded in any species of Periproctia . The armatureof the endopod of leg 4 is also characteristic because the endopod has an unarmed first segment and carries 7 setae on the second segment: this combination has not been found in any congeners ( Table 3 ).