Bonnierilla mollia Ho, 1984

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 : 245-247

Bonnierilla mollia Ho, 1984

( Figs. 163 , 164 )

Material examined. 1 ♀ (dissected and figured) from Polycarpamytiligera (Savigny, 1816) , Chesterfield Corail II cruise, Stn DW164, (19°41.5’S 158°18.8’E), 2 August 1988.

Description of female. Body ( Fig. 163A ) compressed. Body length about 4.1 mm. Prosome inflated lengthwise, consisting small cephalosome and unsegmented metasome. Metasome graduallynarrowing in posterior half (in lateral view): cuticle soft, covered with mucus-like material. Free urosome ( Fig. 163B ) 5- segmented; articulation between last 2 abdominal somites obscure. Caudal rami divergent and widely separated from each other; each ramus ( Fig. 163C ) tapering, about 2.3 timeslongerthan wide (233×100 μm), armedwith 6 small naked setae; outer lateral and dorsal setae located at 31 and 49% of ramus length, respectively.

Rostrum weakly defined, destroyed during dissection. Antennule ( Fig. 163D ) 6-segmented, third segment bearing traces of 2 segmental articulations; armature formula 3, 15, 15+2 aesthetascs, 2, 2+aesthetasc, and 7+aesthetasc; all setae naked. Antenna 4-segmented ( Fig. 163E ); coxa and basis unarmed; first endopodal segment with 1 small seta subdistally; compound distal endopodal segment about 3 times longer than wide, armed with 6 small setae plus small terminal claw less than half length of segment.

Labrum ( Fig. 163F ) with prominent, naked posteromedial lobe; posterolateral surfaces setulose. Mandible ( Fig. 163G ) with 5 teeth and 1 proximal seta on coxal gnathobase; basis and first endopodal segment fused, armedwith 5 setae (arranged 1 + 4); second endopodal segment with 9 setae; exopod with 5 setae, 2 distalsetae unequal in length, both shorter than other 3. Paragnath ( Fig. 163H ) bearing 2 dentiform processes apically. Maxillule ( Fig. 163I ) as usual for genus: 9 setae on arthrite, 3 on basis, and 4 each on exopod and endopod. Maxilla ( Fig. 163J ) 5-segmented; syncoxawith 9 setae (3, 1, 2, and 3), basis with spinulose claw plus 2 setae (1 minute); endopodwith 1, 1, and 3 setaeonfirst to third segments, respectively. Maxilliped ( Fig. 163K ) incompletely 2-segmented with 10 setaeonfirst segment and 2 on second.

Legs 1–4 with 3 segmented rami ( Fig. 164 A-C). Leg 1 as usual for genus. Inner coxal seta present only in legs 3 and 4. Exopods of legs 2–4 swollen, more than twice as long as endopods, and characteristically armed only with inner setae, lacking outer and distal spines. Third exopodal segment of legs 2–4 with rounded outer and distal margins. Endopods of legs 2–4 not extending beyond distal border of first exopodal segment. Armature formula for legs 1–4 as follows:

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

Leg 5 ( Fig. 163L ) 2-segmented; protopod short with small, thin outer distal seta and inner distal row of minute spinules; exopodal segment about 4 timeslongerthan wide (389×98 μm), widestatproximal third; armedwith 1 small, thin apical seta, and ornamented with 7 groups of minute spinules along inner margin.

Male. Unknown.

Remarks. This species is characterised by the lack of outer spines on the exopods of legs 2–4. No significant differences were found between the original description of this species by Ho (1984) and our single female from New Caledonia. The type locality of this species is Sado Island in Japan.

Figures

FIGURE 163. Bonnierilla mollia Ho, 1984, female. A, habitus, right; B, urosome, ventral; C, left caudal ramus, ventral; D, antennule; E, antenna; F, labrum; G, mandible; H, paragnath; I, maxillule; J, maxilla; K, maxilliped; L, leg 5. Scale bars: A, 0.5 mm; B, 0.2 mm; C-K, 0.05 mm; L, 0.1 mm.

FIGURE 164. Bonnierilla mollia Ho, 1984, female. A, leg 1; B, leg 2; C, leg 4. Scale bars: 0.1 mm.