Bysone bidens Kim & Boxshall 2020, sp. nov.
Creators: name: Kim, Il-Hoi
name: Boxshall, Geoff A.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Copepoda
Cyclopoida
Notodelphyidae
Bysone
Bysone bidens

description: Bysonebidens sp. nov.
(Figs. 294, 295)
Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21356), paratype (intact ♀, MNHN-IU-2014-21357), and dissectedparatype (♀, figured) from Chorizocarpaguttata Michaelsen, 1904, Canal Woodin, New Caledonia, depth 18m, Monniot coll., 11 March 1987.
Etymology. The specific name is the combination of Latin words bi (=double) and dens (=a tooth), referring to the pair of ventrodistal denticles on the surface of the labrum.
Description of female. Body (Fig. 294A) with stout prosome and elongate urosome; body length 1.48 mm. Prosome 0.93 mm long: cephalosome clearly defined from inflated metasome; first and second pedigerous somites defined, but third and fourth pedigerous somites completely fused forming brood pouch. Free urosome (Fig. 294B) slender, 5-segmented: genitalsomite 68×294 μm, much wider than long; 4 abdominal somites gradually narrowing, 84×193, 84×123, 82×110, and 68×105 μm, respectively. Caudalramus (Fig. 294C) gradually narrowing distally, 3.6 times longer than wide (130×36 μm): armed with 6 setae; proximal and dorsal setae located at 32 and 63% of ramus length, respectively; all setae shorter than width of ramus at base.
Rostrum (Fig. 294D) 64×89 μm, tapering, with rounded and sclerotized distal margin. Antennule (Fig. 294E) 170 μmlong, 6-segmented; armatureformula 3, 17, 7+aesthetasc, 3, 2+aesthetasc, and 11+2 aesthetascs; setae naked and relatively short; setae on first segment not enlarged. Antenna (Fig. 294F) 4-segmented; coxa, basis, and first endopodal segment unarmed; compound distal endopodal segment 3.1 times longer than wide: armed with 5 setae (2 located at base of terminal claw) plus terminal claw, 33 μm long.
Labrum (Fig. 294G) bearing smooth ventral lobe, pair of ventrodistal denticles near midline, patches of minute setules ventrodistally, and with concave posterior margin. Mandible (Fig.294H)withbroadcoxalgnathobasebearing 5 teeth and 1 distal, spinule-like subsidiary denticle: basis with 1 setaonmedial margin; exopod armedwith 4 setae; setae becoming gradually shorter from proximal to distal; endopod armed with 2 and 5 setae on first and second segments, respectively; middle setaon second endopodal segment markedly longer than other endopodal setae. second exopodal segment with short trace of articulation on outer side. Legs 2–4 with rudimentary inner coxal seta (Fig. 295C, D); outer seta on basis also small; all setae on endopod naked; outer setae on exopod small and bluntly tipped. Second endopodal segment of leg 4 elongated, about 4 times longer than first. Armature formula for legs 1–4 as in B. brevicaudatus sp. nov., except formula IV, I, 4 for second exopodal segment of leg 1. Leg 5 (Fig. 295E) small, consisting of 1 seta located on slight ventrolateral lobe and lobate tapering exopod, notarticulated at base, armed distally with 2 unequal setae.
Male. Unknown.
Remarks. Bysone bidens sp. nov. is more similar to B. brevicaudatus sp. nov. than to B. operculatus; both share several character states including the 3-segmented endopod of the maxilla (2-segmented in B. operculatus), the presence of a claw on the maxillary basis (only setae present in B. operculatus), the inner coxalseta is present in allswimming legs (present onlyin leg 1 in B. operculatus), and the second endopodal segment of leg 1 is armed with 7 setae (compared with 6 setaein B. operculatus).
The salient differences between B. brevicaudatus sp. nov. and B. bidens sp. nov. are 7 setae on the maxilliped in the latter (vs. 9 setae in B. brevicaudatus sp. nov.), 4 setae on the second exopodal segment of leg 1 (vs. 3 setae in B. brevicaudatus sp. nov.), and a protopodal seta in leg 5 (vs. this seta absent in B. brevicaudatus sp. nov.).
description: Published as part of 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), pp. 1-6 in Megataxa 4 (1) on pages 444-446, DOI: 10.11646/megataxa.4.1.1, http://zenodo.org/record/4591138