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 Loboixyssibogae sp. nov. ( Figs. 351 , 352 ) Typematerial . Holotype (intact ♀ , MNHN-IU-2014- 21395 ) , paratypes (9 intact ♀♀ , MNHN-IU-2014-21396), and dissected paratypes ( 3 ♀♀ , figured) from Diplosoma sp., south coast of Timor, Siboga Stn 296 ( 10°14’S , 124°5.5’ E ), depth 8-36 m , 24-26 January 1900 . Etymology . This species is named after the “Siboga Expedition” during which the type specimens were collected. Description of female . Body ( Fig. 351A ) of ovigerous adult extremely swollen. Smaller young adult ( Fig. 351B ) stout, but not as swollen. Body surface densely ornamented with minute setules. Prosome of ovigerous adult 1.57 mm long; dorsal cephalic shield bearing acutely pointed, paired horn-like processes posterolaterally ( Fig. 351C ). Metasome with 2 or 3 dorsal constrictions, marking original articulations between somites; fourth pedigeroussomite (or fusedthirdand fourthpedigerous somites) greatly expanded, almost spherical, forming brood pouch. Free urosome ( Fig. 351D ) small, inserted into ventral surface of prosome, 5- segmented, but posterior articulations indistinct. Genital somite 49×193 μm; abdominal somites covered with minutesetules, 36×167, 58×149, 33×138, and 73×135 μm, respectively. Caudalramus ( Fig. 351E ) stronglytapering, about 1.8 times longer than wide (71×40 μm) and as long as anal somite, densely covered with setules; narrowed distal part pale and with thin cuticle: caudal setae not discernible from setules. Rostrum ( Fig. 351F ) aslongas wide, denselysetulose, weak, flexible, with rounded distal margin. Antennule ( Fig. 351G ) stronglytapering, incompletely 7-segmented, 160 μm long; setae not discernible from setules. Antenna ( Fig. 351H ) 3-segmented, consistingof coxa, basis, and unsegmented endopod; endopodal segment 2.9 times longer than wide (55×19 μm) and 0.7 times as long as basis: armedwith 6 setae (grouped as 1, 2, and 3) plus small terminal claw, one-third as long as endopod. Labrum ( Fig. 351I ) with broad convex posterior margin; posterior region soft, flexible, densely setulose. Mandible ( Fig. 351J ) with 5 acute teeth and 1 small setaon coxalgnathobase: basiswith 1 medial seta: exopodwith 5 setae, outersetaeslightlyshorterthan others:endopodwith 1 and 4 setae on first and second segments, respectively; proportional lengths of setae on second segment 3:4:6:5 from inner to outer. Maxillule ( Fig. 351K ) with 7 setae on arthrite, 1 each on epipodite and basis, 4 on exopod and 3 on endopod; coxal endite absent; 3 setae on endopod unequal (medial seta shortest and outer seta longest). Maxilla ( Fig. 352A ) 4-segmented; syncoxawith 4, 2, and 2 setaeon first to third endites, respectively; basis with thick seta plus 1 small seta; endopod 2-segmented with thick seta on first segment and 1 thick and 2 shorter, thin setaeon second. Maxilliped ( Fig. 352B ) as unsegmented lobe bearing 5 or 6 (commonly 6) setae mediodistally and ornamented with fine spinules on distal and outer surfaces. Leg 1 ( Fig. 352C ) with incompletely 3-segmented rami; inner distal spine on basis 15 μm long, bilaterally serrate; both rami ornamented with slender setules; second exopodal segment lacking outer element. Inner coxal seta absentin legs 1–4. Legs 2–4 with 3-segmented exopods and 2-segmented endopods ( Fig. 352D, E ); secondendopodal segment of legs 2 and 3 with vestige of articulation: first exopodal segment lacking inner seta. Second exopodal segment bearing minute inner seta in legs 2 and 3, but lacking in leg 4. Legs 2 and 3 with same armature formula. Proximal 2 inner setae on endopod of legs 2 and 3 minute. Armature formula for legs 1–4 as follows:
Coxa Basis Exopod Endopod
Leg 1 0-0 Legs 2 & 30-0 Leg 4 0-0 1-I 1-0 1-0 1-1; 0-1; 2, 1, 3 1-0; 1-1; 3, 1, 5 1-0; 1-0; 2, 1, 5 0-1; 0-1; 1, 2, 2 0-1; 1, 2, 4 0-0; 1, 2, 2
Leg 5 ( Fig. 351D ) represented by 2 small lobes positioned posteroventrally on somite; outer lobe tipped withsmall protopodal seta, and inner (exopodal) lobe tipped with 2 small setae. Male . Unknown. FIGURE 351. Loboixys sibogae sp. nov . , female. A, habitus, right; B, habitus of young adult, right; C, cephalic horn; D. leg 5 and urosome, ventral; E, right caudal ramus, dorsal; F, rostrum; G, antennule; H, antenna; I, labrum; J, mandible; K, maxillule. Scale bars: A, 0.5 mm; B, 0.2 mm; C, E–K, 0.02 mm; D, 0.1 mm. FIGURE 352. Loboixyssibogae sp. nov . , female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, leg 4. Scale bars: A, C–E, 0.05 mm; B, 0.02 mm. Remarks . Loboixys sibogae sp. nov. differs from the type species L . ryukyuensis , in the setation of the first exopodal and endopodal segments of leg 1, each of which bears an innerseta (cf. absentin L . ryukyuensis ), the caudal rami are distinct (fused to anal somite in L . ryukyuensis ), the first endopodal segment of leg 4 is unarmed (cf. bears an inner seta in L . ryukyuensis ), and leg 5 is bilobed (leg 5 consists of 1 inner seta and an apparently bipartite outer lobe in L . ryukyuensis ). The third exopodal segment of leg 4 of L . ryukyuensis is armed with 9 setae (formula 3, 1, 5), such a setation pattern is extremely unusual for a member of the Notodelphyidae .