Bonnierilla similis Illg & Dudley, 1961

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 : 247-249

Bonnierilla similis Illg & Dudley, 1961

( Figs. 165 , 166 )

Material examined. 6 ♀♀ (MNHN-IU-2018-1840) and 1 dissected ♀ (figured) from Pyura microcosmus (Savigny, 1816) , Taureau, Roscoff, France.

Description of female. Body ( Fig. 165A ) compressed, 2.58 mm long. Cephalosome produced into blunt projections at posterolateral corners of dorsal shield. Metasome consisting of well-defined first to fourth pedigerous somites in unexpanded specimen; greatest dorsoventral depth of metasome 0.55 mm. Free urosome 5-segmented: 4 abdominal somites becoming gradually shorter and narrower posteriorly. Caudal ramus ( Fig. 165B ) elongate, slightlycurvedventrally, gradually narrowing distally and 4.8 times longerthan wide (226×47 μm); armed with 6 naked setae, outer lateral and dorsal setae located at 37 and 58% of ramus length, respectively; longest distal seta about 0.35 times as long as ramus.

Rostrum ( Fig. 165C ) longerthanwide, tapering. Antennule 8-segmented; first and second segments much broader than distal 6 segments; setation not elucidated due to damage to specimens. Antenna ( Fig. 165D ) 4- segmented; last segment (compound distal endopodal segment) forming broad, rounded subdistal tubercle armed with 3 setae, distal margin with 5 setae, 3 equal in length, broad, rod-shaped, and fused at base ( Fig. 165E ); terminal claw short and stout.

Labrum not examined. Mandible ( Fig. 165F ) 5 teeth, 1 subsidiary tooth between distal first and second teeth; basiswith 1 medial seta; exopod with3 longproximal setae and 2 unequal, shorter setae distally; endopod obscurely articulated with basis, armedwith 4 and 9 setaeon first and second segments, respectively. Paragnath ( Fig. 165G ) with large, claw-like apical process. Maxillule ( Fig. 165H ) as usual for genus, but arthrite bearing 10 setae; seta on coxal endite broad; proximal seta on basis much shorter than distal 2. Maxilla ( Fig. 165I ) also as usual for genus; 9 setae on syncoxa arranged as 3, 1, 2, and 3; claw on basis finely spinulose along both margins; 3 endopodal segments with 1, 1, and 3 setae, respectively. Maxilliped ( Fig. 165J ) incompletely 2-segmentedwith 10 setaeon first segment and 2 unequal setae on second.

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

Legs 1–4 with 3-segmented rami ( Fig. 165K , 166A, B ). Inner coxal seta absent in legs 1 and 2, but large seta present in legs 3 and 4. Outer setaon basis slightly shorter than exopod in leg 1 and very small in legs 2–4. Inner distal spine on basis of leg 1 slightly longer than first endopodal segment. Exopod twice as long as endopod in legs 2 and 3, and about 2.4 timeslongerthan endopod in leg 4. Outerspinesonexopods of legs 2–4 very small, mostly rudimentary. Armature formula for legs 1–4 as follows:

Leg 5 ( Fig. 166C, D ) comprising short protopod and free exopod; protopod withnaked outerdistal seta; exopod with naked setaon apex plus 3 or 4 groups of spinules on inner margin; in dissected specimen left exopod more slender than right, 4.24 times longer than wide (144×34 μm); right exopod 3.68 times longerthan wide (140×38 μm): apical seta slightly shorter than exopodal segment.

Male. Unknown.

Remarks. This species has a characteristic feature that serves to differentiate it from all of its congeners, the 3 strong rod-shaped distal setae on the distal margin of the antenna. Originally this species was reported from Pyura squamulosa Alder, 1863 collected on the Mediterranean coast of France ( Illg & Dudley, 1961). Holmes & Gotto (1987) subsequently reported it from Irish waters.

Figures

FIGURE 165. Bonnierilla similis Illg & Dudley, 1961, female. A, habitus, right; B, caudal ramus; C, rostrum; D, antenna; E, distal part of antenna; F, mandible; G, paragnath; H, maxillule; I, maxilla; J, maxilliped; K, leg 1. Scale bars: A, 0.2 mm; B, D, F, H-K, 0.05 mm; C, 0.1 mm; E, G, 0.02 mm.

FIGURE 166. Bonnierilla similis Illg & Dudley, 1961, female. A, leg 2; B, leg 4; C, right leg 5; D, left leg 5. Scale bars: 0.05 mm.