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 Paranotodelphys stenosa sp. nov. ( Figs. 38 , 39 ) Typematerial . Holotype (intact ♀ , MNHN-IU-2009- 5054 ) , paratypes (5 intact ♀♀ , MNHN-IU-2014- 21223) , and dissected paratypes ( 2 ♀♀ , figured) from Ecteinascidia diaphanis Sluiter, 1886 (MNHN-IT-2008- 3823 = MNHN P2/ ECT /108), Blue Water mangrove channel, Gam Island, West Papua , Indonesia ( 0°29.164 Ś , 130°39.865 É ), depth 0.5 m, CRRF BMC , L.J. Bell & LE . Martin coll., 07 December 2007 . Etymology . The name is derived from the Greek sten (= narrow), alluding to the narrow body shape of the new species. Descriptionoffemale . Body ( Fig. 38A, B ) slender, 2.20 mm long in dissected specimen; with mean body length of 2.05 mm (1.61–2.58 mm) based on 7 specimens . Cephalosome and anteriorthree pedigeroussomites dorsoventrally depressed. First pedigerous somite lacking epimera. Second and third pedigerous somites each with well-developed, posterolaterally extended epimera. Brood pouch incorporating fifth pedigerous somite elongate, cylindrical, 1277×400 μm, more than twice as long as anterior part of prosome. Free urosome ( Fig. 38C ) 5- segmented, 48×128, 46×108, 48×104, 44×94, and 77×90 μm, respectively: anal somite slightly wider than long; other 4 urosomites much wider than long. Caudal rami divergent and elongate; each ramus about 9 times longer than wide (285×31 μm) and about 3.7 times as long as anal somite, denselysetulose along inner margin; armed with 6 setae, innermost distal seta (seta VI) pinnate, other setae naked; outer lateral seta located at 28% of ramus length. Rostrum ( Fig. 38D ) triangular, longerthanwide, 92×73 μm, well-defined from cephalosome, with angular apex. Antennule ( Fig. 38E ) 9-segmented, but second segment subdivided by partial suture line; armature formula 3, 17, 6, 4+aesthetasc, 4, 2+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; aesthetascs thin, difficult to distinguish from setae; about half of setae pinnate. Antenna ( Fig. 38F ) 4-segmented; coxa unarmed; exopod represented by 2 small pinnate setae of equal length at outer distal corner of basis; first endopodal segment slightly expanded laterally, armed with 1 seta on outer side; compound distal endopodal segment about 2.9 times longer than wide (63×22 μm), gradually broadening distally; armed with 10 setae and short terminal claw, aboutone-thirdaslongas segment. Labrum ( Fig. 39A ) denselysetulose posterolaterally, with concave posterior margin and small posteromedian lobe. Mandible ( Fig. 38G ) with 5 teethand 2 small proximal setae on coxal gnathobase, distalmost tooth acutely pointed and accompanied by small denticle on distal margin of gnathobase ( Fig. 39B ); basis with 1 seta on medial margin and 1 rounded tubercle proximally on outer margin (indicated by arrowhead in Fig. 38G ); exopod indistinctly 2-segmented, first segment with 1 seta and row of setules; second segment with 4 setae, distalmost seta markedly larger; endopod 2-segmented, with 2 and 8 setae on first and second segments, respectively; articulation incomplete between basis and firstendopodal segment. Maxillule ( Fig. 38H ) with 7 setae on precoxal arthrite, 1 seta on coxal endite, 2 setae on epipodite, 3 setae on medial margin of basis; small exopodwith 4 distalsetae; endopod unsegmented, with 6 setae (3 distal setae longer than other 3). Maxilla ( Fig. 39C ) as usual for genus, with 3 setae on first endite of syncoxa and 1, 1, and 3 setae, respectively, on first to third segments of endopod. Maxilliped ( Fig. 39D ) with 9, 0, and 3 setae on first to third segments, respectively; first segment ornamented with few rows of minute spinules distally; second segment with weak outer distal swelling and long setules on medial margin; third segment small and incompletely articulated from second segment. Legs 1–4 with 3-segmented rami ( Fig. 39 E–G). Inner coxal seta pinnate in legs 1 and 2, small and pinnate in leg 3, and rudimentary in leg 4. Outer seta on basis of legs 2–4 small and naked. Inner distal spine on basis of leg 1 large, longerthan first endopodal segment, with minute spinules on both margins. Outer distal spine on first exopodal segment of legs 1–4 and second exopodal segment of legs 2–4 strong and slightly curved outwards. Distal spine on third exopodal segment of leg 1 stout and pinnate along outer margin. Spines on third exopodal segment of legs 2–4 pectinate along outer margin. Armature formula for legs 1–4 as in generic diagnosis. Leg 5 ( Fig. 39H ) represented by 2 papillae on posteroventral border of brood pouch, each tipped with small, naked seta. Male. Unknown. Remarks . This species may be characterised by the extremely long caudal rami which are about 9 times as long as wide and 3.7 times as long as the anal somite. These proportions differ from all known congeners. The possession of 2 small exopodal setae of equal length on the antenna and the prominent proximal tubercle on the outer margin of the mandibular basis are additional diagnostic features of the new species.