Bonnierilla acollaris Schellenberg, 1922

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 : 239-242

Bonnierilla acollaris Schellenberg, 1922

( Figs. 159 , 160 )

Material examined. 1 ♀ from Halocynthia spinosa Sluiter, 1905 , Ibo, Mozambique, 11 November 1995.

Descriptionoffemale. Body ( Fig. 159A ) swollen, compressed, 3.00 mmlong; prosome 2.50 mmlong, consisting of incompletely defined cephalosome and metasomeforming brood pouch. Metasome unsegmented, expanded dorsally with dorsoventral depth of 1.20 mm; bearing 3 lobate expansions ventrally, one at base of each of legs 2 to 4. Fifth pedigerous somite fused to metasome. Freeurosome ( Fig. 159B ) broad, 5-segmented; all urosomites much wider than long; genital somite very short. Anal somite ornamented with patch of small spinules posteriorly on outer surface and 2 patches of fine granules dorsally on each side: anal operculum large. Caudal rami widely separated from each other, about 1.5 times longer than anal somite; each ramus tapering, with rounded distal margin ( Fig. 159C ); armed with 6 small setae; largest seta about half as long as maximum width of ramus; outer lateral and dorsal setae positioned at 40 and 70% of ramus length, respectively.

Rostrum ( Fig. 159D ) as long as wide (130×130 μm), almost triangular, narrowing abruptly in distal third. Antennule ( Fig. 159E ) small, 295 μm long and 8- segmented; armatureformula 3, 16, 10+aesthetasc, 5, 2+aesthetasc, 2, 3, and 7+aesthetasc; first and second segments much broader than distal segments; articulations between distal 6 segments indistinct; all setae naked. Antenna ( Fig. 159F ) ratherslender, 4-segmented; coxa short and unarmed; basis more than twice as long as wide, armed with 2 minute setal vestiges at outer distal corner; first endopodal segment about 1.8 times longer than wide (98×56 μm), armedwith 1 small seta; compound distal endopodal segment about 3.5 times longerthan wide (127×36 μm), distinctly narrower than first, armed with 9 small setae (distal 3 setae blunt at tip, not longer than terminal claw) plus small terminal claw less than half as long as segment.

Labrum ( Fig. 159G ) ornamented with setules on posterior marginand posterolateral surfaces, and with densely spinulose posteromedian lobe. Mandible ( Fig. 159H ) with coxa bearing 5 major teeth and 2 small proximal setae, 1 small subsidiary tooth between first and second teeth, and 2 thin spinules between second and third teeth; basis with 1 seta mediodistally; exopod 4-segmented with 5 subequal setae; endopod 2-segmented with 4 and 9 setae on first and second segments, respectively; firstendopodal segment broad. Maxillule ( Fig. 159I ) with 10 setae on arthrite, 1 broad, strongly tapering setaon coxal endite, 2 unequal setae on epipodite, 3 setae on medial margin of basis, and 4 setae each on exopod and endopod. Maxilla ( Fig. 159J ) 5-segmented; syncoxawith 4 (including small, needlelike distal seta), 1, 2, and 3 setae on first to fourth endites, respectively; basis with 1 slender clawplus 2 unequal setae; endopodwith 1, 1, and 3 setaeonfirst to third segments, respectively. Maxilliped ( Fig. 160A ) incompletely 2-segmented; first segment with 10 setae (5 medial and 5 mediodistal) and ornamented with rows of minute spinules proximally; second segment narrow and ornamented with setules onmedial margin, bearing 2 unequalapicalsetae.

Leg 1 ( Fig. 160B ) with 3-segmented rami: lacking inner coxal seta; basis with large outer seta almost as long as exopod, ornamented with setules on distal inner margin; innerdistal spine 86 μm long, spinulose along medial margin and extending to distal border of second endopodal segment. Exopod about 1.4 timeslongerthan endopod; first exopodal segment about twice as long as wide. Endopod narrow, tapering; 3 distal setae on third segment enlarged.

Legs 2–4 ( Fig. 160 C-E) with 3-segmented rami. Inner seta on coxa absent in leg 2, but present in legs 3 and 4. Outer seta on basis small and naked. Exopod about 1.4 times longer than endopod in leg 2, about 1.6 times longer in leg 3, and 1.7 times longer in leg 4. Outer and distal setae on exopods very small, blunt at tip; inner setae on third exopodal segment also small and naked. Armature formula for legs 1–4 as follows:

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

Leg 5 ( Fig. 160F ) consisting of short protopod and freeexopodal segment; protopod bearingsmallouterdistal seta and mediodistal row of spinules near base of exopod. Exopod about 3.5 times longer than wide (152×44 μm), slightly narrowing in middle, ornamented with 5 rows of spinules on medial surface and 2 small apical setae, inner seta naked, outer seta 45 μm long, slightly longer than inner seta, pinnate distally.

Male. Not available.

Remarks. In the original description of B. acollaris by Schellenberg (1922) several diagnostic features of this species were recorded: (1) the last third of the lateral margin of the anal somite is spinulose; (2) the longest seta on the caudal ramus is half as long as the ramus is wide; (3) the proximal endite of the maxilla bears 4 elements; (4) all setation elements on the third exopodal segment of legs 1–4 are naked; (5) the third exopodal segments of legs 3 and 4 bear 2 outer spines and 1 apical spine plus 4 setae; and (6) the outer spines on the exopodal segments of the female leg 3 are very small (as figured by Schellenberg).

These morphological characteristics are all shared by our single specimen from Mozambique, supporting its identification as B. acollaris . This species was originally found in Ascidia malaca (Traustedt, 1883) , A. glabra Hartmeyer, 1922 and Ascidiella aspersa from the southwestern coast of Australia ( Schellenberg, 1922).

Figures

FIGURE 159. Bonnierilla acollaris Schellenberg, 1922, female. A, habitus, right; B, urosome, ventral; C, right caudal ramus, ventral; D, rostrum; E, antennule; F, antenna; G, labrum; H, mandible; I, maxillule; J, maxilla. Scale bars: A, 0.5 mm; B, 0.1 mm; C-H, J, 0.05 mm; I, 0.02 mm.

FIGURE 160. Bonnierilla acollaris Schellenberg, 1922, female. A, maxilliped; B, leg 1; C, leg 2; D, leg 3; E, leg 4; F, leg 5. Scale bars: A, F, 0.05 mm; B-E, 0.1 mm.