Bonnierilla rugosa, 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 : 261

Bonnierilla rugosa sp. nov.

( Figs. 174 , 175 )

Typematerial. Holotype (intact ♀, MNHN-IU-2009- 5053 ) anddissectedparatype (young ♀) from Polycarpa madagascariensis (Michaelsen, 1912) (MNHN-IT-2008-6553 = MNHNS 1 POL.B 547), BENTHEDI, NW Mayotte, Canal of Mozambique, “Suroît”, depth 10-20 m, Vasseur coll., 20 March 1977.

Etymology. The specific name refers to the rugose metasome.

Description of female. Fully grown adult (holotype) body ( Fig. 174A ) compressed, 3.00 mmlong. Prosome comprising small cephalosome and unsegmented metasome inflated lengthwise, 2.6×1.1 mm in lateral view, with narrow posterior third, rounded anterior and posterior margins: 2 pairs of small epimera present representing defined dordsal tergite margins of second and third pedigerous somites. Surface of metasome soft, mucus-like, covered with numerous, hemispherical nodules.

	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; III, I, 5	0-1; 0-2; 1, 2, 3
Leg 3	0-0	1-0	I-1; I-1; II, I, 5	0-1; 0-2; 1, 2, 3
Leg 4	0-0	1-0	I-1; I-1; II, I, 5	0-1; 0-2; 1, 2, 2

Dissected young adult body ( Fig. 174B ) not inflated, narrow,2.04mmlong.Metasomeindistinctly4-segmented; second and third pedigerous somites with ventrolateral epimera. Freeurosome 5-segmented. Caudalramus ( Fig. 174C ) strongly curved ventrally, elongate, about 5.2 times longer than wide (354×68 μm), sclerotized along dorsal margin: armed with 6 naked setae; longest terminal seta 110 μm long; 2 proximal setae located at 37 and 45% of ramus length.

Rostrum ( Fig. 174D ) small, nearly triangular, 75×118 μm, wider than long, with slightly convex lateral margins. Antennule 357 μm long, 9-segmented ( Fig. 174E ); first 2 segments broad and distal 7 segments slender; armatureformula 4, 22+spine, 16, 4, 11+aesthetasc, 3, 5, 5+aesthetasc, and 7+aesthetasc; setae extremely crowded, all naked. Antenna ( Fig. 174F ) 4-segmented; coxa, basis, and first endopodal segment unarmed; compound distal endopodal segment 3.1 times longer than wide (100×32 μm) and 1.2 times longerthan firstendopodal segment; armedwith 9 setae (distal 3 blunt tipped) plusterminal claw about half as long as segment.

Labrum ( Fig. 174G ) ornamented with setules and spinules posteriorly and with indistinct, spinulose posteromedian lobe. Mandibular gnathobase ( Fig. 175A ) with 6 teeth and 2 subsidiary denticles, 1 on either side of largest distalmost tooth: palp ( Fig. 174H ) biramous; basis with broad medial seta; exopod with 5 subequal setae; endopod with 4 and 9 setae on first and second segments, respectively. Paragnath rather elongate, wellsclerotized, withsmall dentiform process mediodistally. Maxillule ( Fig. 174I ) typical of genus, with 9 setae on athrite, 1 on coxal endite, 2 on epipodite, 3 on basis, and 4 each on exopod and endopod. Maxilla ( Fig. 175B ) 5- segmented; syncoxawith 9 setae (arranged as 3, 1, 2, and 3 from proximal to distal); basis withlarge claw plus 1 seta; endopod small with 1, 1, and 3 setae on first to third segments, respectively. Maxilliped ( Fig. 175C ) unsegmentedbut divisible intobroad proximal and narrow distal parts; armedwith 10 medial and 2 apical setae.

Legs 1–4 with 3-segmented rami ( Fig. 175 D-F); all legs lacking inner coxal seta. Outer seta on basis large (longer than exopod) in leg 1, butsmall inlegs 2–4. Inner distalspine on basis of leg 1 extending tomiddle of second endopodal segment, 58 μm long. Inner margin of basis of legs 2 and 3 protuding and well-sclerotized. Exopod slightly longer than endopod in leg 1. Exopods elongated in legs 2–4, twice as long as endopod in legs 2 and 3, and 2.6 times longer in leg 4. Exopodal segments of legs 2–4 ornamented with numerous minute spinules on outer distal surfaces; outer spines on exopodal segments of legs 2–4 small, setiform with blunt tips, and mostly obsolete. Armature formula for legs 1–4 as follows:

Leg 5 ( Fig. 175G ) 2-segmented; protopod short, with 1 naked seta on tapering outer distal process and row of minute spinules near inner distal margin; exopodal segment strongly curved in middle, about 5.7 times longer than wide (215×38 μm), widest at midlength, armed with 2 naked apical setae; ornamented with 5 to 7 rows of minute spinules on inner surface; apical setae on exopod either subequal as in Fig. 175G or very unequal, with one vestigial.

Male. Unknown.

Remarks. Bonnierilla rugosa sp. nov. is similar to B. mollia in having a soft mucus-like covering over the metasome in the fully grown adult female, but these two species are quite different in other respects. In B. rugosa sp. nov. both the caudal ramus and the free exopodal segment of leg 5 are strongly curved and much more elongate than in B. mollia . The exopods of legs 2–4 of B. rugosa sp. nov. are elongate but not expanded and they bear small outer spines, unlike B. mollia which has expanded exopodal segments on legs 2–4 lacking outer spines.

In general, species of Bonnierilla possess an inner seta on the coxa in legs 1 and 2, but lack this inner seta inlegs 3 and 4 ( Table 4). In this respect B. rugosa sp. nov. is unusual because the inner coxal seta is absent in all legs 1–4; this feature is unique within the genus Bonnierilla as defined here. It is also shared with B. armata Schellenberg, 1922 but this species is transferred below to a new genus.

Figures

FIGURE 174. Bonnierilla rugosa sp. nov., female. A, habitus of fully grown adult; B, habitus of young adult; C, caudal ramus; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandibular palp; I, maxillule. Scale bars: A, 0.5 mm; B, 0.2 mm; C, 0.1 mm; D–I, 0.05 mm.

FIGURE 175. Bonnierilla rugosa sp. nov., female. A, mandibular gnathobase; B, maxilla; C, maxilliped; D, leg 1; E, leg 2; F, leg 4; G, leg 5. Scale bars: 0.05 mm.