Bonnierillatenuipedis, 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 : 264

Bonnierillatenuipedis sp. nov.

( Figs. 176 , 177 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21285 ) anddissectedparatype (♀, figured) (caudal rami lost in both) from Ascidia sydneiensis Stimpson, 1855 , west islet of Goeland, New Caledonia, depth 12 m, Thomassin coll., 20 March 1977.

Etymology. The specific name is derived from the Latin tenui (slender) and ped (a foot) and alludes to the slender exopod of leg 5.

Descriptionoffemale.Body( Fig.176A )compressed; length 2.09 mm, excluding caudal rami. Prosome 1.70 mm long, consisting of well-defined cephalosome and unsegmented metasome. Metasome slightly tapering posteriorly, dorsally convex with dorsoventral depth 0.82 mm across middle of metasome. Fifth pedigerous somite fused with metasome. Free urosome ( Fig. 176B ) 5-segmented: genital somite 100×278 μm, longer dorsally than ventrally, with convex posterodorsal margin. Four abdominal somites approximately 212×267, 176×230, 103×185, and 88×155 μm, respectively. Caudal rami missing.

	Coxa	Basis	Exopod	Endopod
Leg 1	0-0	1-I	I-1; I-1; III, I, 4	0-1; 0-1; 1, 2, 3
Leg 2	0-0	1-0	I-1; I-1; I, I, 5	0-1; 0-2; 1, 2, 3
Leg 3	0-1	1-0	I-1; 0-1; I, I, 5	0-1; 0-2; 1, 2, 3
Leg 4	0-1	1-0	I-1; I-1; I, I, 5	0-1; 0-2; 1, 2, 2

Rostrum ( Fig. 176C ) semicircular, distinctly wider than long (101×172 μm), with broadly rounded distal margin. Antennule ( Fig. 176D ) 233 μm long, 8- segmented; armatureformula 3, 16+spine, 10+aesthetasc, 5, 3+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; first and second segments markedly broader than distal segments; setae crowded, naked and mostly long; spine on second segment blunt and pectinate along one margin. Antenna ( Fig. 176E ) stout, 4-segmented; coxa and basis unarmed; first endopodal segment with 1 seta subdistally; compound distal endopodal segment relatively short, about 2.3 times longerthan wide (74×32 μm) and as long as first segment; armedwith 8 setae (all attenuated) plus terminal claw 67 μm long, 0.9 times as long as segment.

Labrum ( Fig. 176F ) with patches of setules posterolaterally and spinules posteromedially. Mandible ( Fig. 176G ) with 5 teeth and 1 smallseta on coxal gnathobase; basis with few setules proximally and 1 seta on distally onmedial margin; exopod 2-segmented, with 3 and 2 setae on proximal and distal segments, respectively, outer seta on small distal segment shorter than other 4; endopod incompletely articulated from basis, with 4 and 9 setaeon firstand second segments, respectively. Paragnath ( Fig. 176H ) with strong, dentiform process mediodistally and setules along medial margin. Maxillule ( Fig. 176I ) not specialized; armed with 10 setaeon arthrite, 1 on coxal endite; 2 on epipodite, 3 on basis, and 4 each on exopod and endopod; proximal seta on basis small, one-third as long as distal 2 setae. Maxilla ( Fig. 176J ) not specialized, armed with 3 setae on first endite of syncoxa and on third segment of endopod. Maxilliped ( Fig. 177A ) distinctly 2-segmented with 10 setae on first segment and 2 equal setaeon second,

Legs 1–4 ( Fig. 177 B-E) with 3-segmented rami. Inner coxal seta absent in legs 1 and 2, but present in legs 3 and 4. Outer seta on basis large, broad, slightly longer than exopod in leg 1, but very small in legs 2–4. Inner distal spine on basis of leg 1 smooth, 45 μm long, extending to middle of second endopodal segment. Exopod 1.4 times longer than endopod in leg 1, about 1.6 times longer in legs 2 and 3, and 1.7 times longer in leg 4. First exopodal segment of legs 2–4 as long as second and third exopodal segments combined, and about 2.7, 2.9 and 3.6 times as long as wide in legs 2–4, respectively; ornamented with minute spinules scattered over anterior (ventral) surface. Third exopodal segment of legs 2–4 slender. Inner setae on exopodal segments of legs 2–4 small, shorter than segment. Outer margin of endopod naked in leg 1, but densely setulose in legs 2–4. Armature formula for legs 1–4 as follows:

Leg 5 ( Fig. 177F ) 2-segmented; protopod short, with 1 smallseta at outerdistal cornerand row of small spinules at inner distal corner; exopodal segment elongate, slender, about 6.1 timeslonger than wide (141×23 μm), withnaked apical seta and 4 rows of spinules on inner margin.

Male. Unknown.

Remarks. This new species is characterised by the elongatefree exopodal segment of leg 5, which is more than 6 times longer than wide. Although a similarly elongate exopod is also present on leg 5 in B. filipes Stock, 1967 , the latter species has 2 pinnate setae on the exopod of leg 5 compared to onlya single naked seta in the new species, and exhibits many other different character states (see below). Bonnierilla rugosa sp. nov. also has an elongate exopod of leg 5, but its exopod is strongly curved, and the caudal rami are also strongly curved, whereas in B. tenuipedis sp. nov. the exopodal segment of leg 5 is not curved.

Figures

FIGURE 176. Bonnierilla tenuipedis sp. nov., female. A, habitus, right; B, urosome, ventral; C, rostrum; D, antennule; E, antenna; F, labrum; G, mandible; H, paragnath; I, maxillule; J, maxilla. Scale bars: A, 0.2 mm; B, 0.1 mm; C–G, I, J, 0.05 mm; H, 0.02 mm.

FIGURE 177. Bonnierilla tenuipedis sp. nov., female. A, maxilliped; B, leg 1; C, leg 2; D, leg 3; E, leg 4; F, leg 5. Scale bars: 0.05 mm.