Bonnierilla iboensis sp. nov.

(Figs. 167–169)

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21281), paratypes (intact, 2 ♀♀, 2 ♂♂, MNHN-IU-2014- 21282), and dissected paratypes (1 ♀, 1 ♂, figured), from Styela canopus (Savigny, 1816) (MNHN-IT-2008-8134 = MNHNS1/STY/273), AURACEA 1995, Matemo cliff, Ibo Island, Mozambique, depth 10–20 m, C. Monniot coll., 18 November 1995.

Etymology. The specific name refers to the type locality, Ibo.

Descriptionoffemale. Body (Fig. 167A) stout, compressed; length 2.16 mm. Prosome 1.47 mmlong, consisting of cephalosome and unsegmented metasome with rounded posterior margin. Free urosome (Fig. 167B) 5-segmented, narrowing only slightly posteriorly; lengths of somites from genital to anal somite 106, 182, 120, 90, and 90 μm. Caudalramus (Fig. 167C) elongate, curved ventrally, tapering, about 4.6 times longer than wide (206×45 μm) and more than twice as long as anal somite; armed with 6 naked setae, all setae shorter than width of ramus at base; outer lateral and dorsal setae located at 35 and 54% of ramus length, respectively.

Rostrum (Fig. 167D) longerthanwide (130×109 μm) with rounded apex.Antennule (Fig. 167E) 320 μm long, 8- segmented; first and second segments much broader than distal segments; armatureformula 3, 16, 8+aesthetasc, 4, 2+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; all setae naked. Antenna (Fig. 167F) slender, 4-segmented; coxa short and unarmed; basis with 1 tiny vestigial seta distally; first endopodal segment with convex outer marginand 1 subdistal seta; compounddistalendopodal segment about 3.3 timeslongerthan wide (95×29 μm) and 1.7 timeslongerthan first; armedwith 8 setae (all shorter than terminal claw and distal 3 setae with blunt tip) plus terminal claw, half as long as segment.

Labrum (Fig. 167G) withsetulose posteromediallobe and posterior margin. Mandible (Fig. 167H) with 5 teeth oncuttingmargin of coxa; basis with 1 medial seta; exopod 2-segmented, armed with 2 and 3 setae on first and second segments, respectively; endopodwith 4 and 9 setaeon firstandsecondsegments, respectively. Paragnath (Fig. 168A) with acute apical process. Maxillule (Fig. 167I) with 9 setae on arthrite, 1 broad seta on coxal endite, 2 on epipodite, 3 on basis, and 4 each on exopod and endopod. Maxilla (Fig. 167J) 5-segmented, with 9 setae (3, 1, 2, and 3) on syncoxa, clawplus 2 setaeon basis, and 1, 1, and 3 setae on first to third endopodal segments, respectively. Maxilliped (Fig. 168B) unsegmented with broad proximal and narrow distal parts, armed with 10 medial and 2 apical setae.

Legs 1–4 with 3-segmented rami (Fig. 168 C-E); exopod about 1.3 times longer than endopod in leg 1, about 1.7 times longer in legs 2 and 3, and twice as long in leg 4. Inner coxal seta absent in legs 1 and 2 but present in legs 3 and 4. Outer seta on basis large, pinnate in leg 1, but small and naked in legs 2–4. Inner distal spine on basis of leg 1 extending to distal border of second endopodal segment, 73 μm long. Outer spines on exopods of legs 2–4 rudimentary or absent on some segments. All setae on third exopodal segments of legs 2–4 naked. Armature formula for legs 1–4 as follows:

Leg 5 (Fig. 168F) 2-segmented; short protopod with outer distal seta and inner distal row of small spinules; exopodal segment tapering markedly, about 2.5 times longerthan wide (136×55 μm), with apical seta plus rudimentary seta distally, and ornamented with 3 rows of minute spinules on inner margin.

Descriptionofmale. Body (Fig. 169A) narrow, 1.25 mm long. Prosome consisting of dorsoventrally depressed cephalosome and 4-segmented cylindrical metasome. Urosome (Fig. 169B) 6-segmented: fifthpedigerous somite well-defined, widerthan genital somite; genital somite 93×166 μm, with well-developed genital opercula; 4 abdominal somites gradually narrower and shorter, 107×114, 90×108, 52×95, and 45×84 μm, respectively. Caudal ramus (Fig. 169C) about 6 timeslongerthan wide (145×24 μm) and about 3.2 times longerthan anal somite; outer lateral and dorsal setae positioned as in female.

Rostrum, antennule, antenna, labrum, mandible, maxillule, and maxilla as in female. Maxilliped (Fig. 169D) unsegmented as in female, but armed with 8 medial and 2 apical setae.

Leg 1 as in female. Legs 2–4 (Fig. 169 E-G) with welldeveloped outer spines on exopods. Exopod 1.6 times longerthan endopod in legs 2 and 3, and 1.9 times longer inleg 4. Armature formula for legs 2–4 as follows:

Leg 5 (Fig. 169B) asin female. Leg 6 (Fig. 169B) represented by 2 naked setae on genital operculum.

Remarks. Bonnierilla iboensis sp. nov. has the typical morphological features of Bonnierilla, i.e., the mandible has 4 setae on the first endopodal segment and 9 setae on the second; the maxillule bears 4 setae each on the exopod and endopod; the maxilliped of the female has 10 medial and 2 apical setae; the inner coxal seta is absent in legs 1 and 2 but present in legs 3 and 4; the third endopodal segment of leg 1 bears 6 setae; and the endopod of leg 4 is armed with 1, 2, and 5 elements respectively on the first to third segments.

Eleven previously described species are valid within the genus Bonnierilla, of which only three species ( B. acollaris, B. mollia and B. similis) have the endopod of the mandible armedwith 4 and 9 setae on the first and second segments, respectively, plus the maxillule bearing 4 setae on both the exopod and endopod, as in B. iboensis sp. nov. (see Table 4). Bonnierilla similis can be distinguished from B. iboensis sp. nov. by its characteristic antennal setation and by the possession of 5 setae on the third endopodal segment of leg 1 (rather than 6 as in the new species). The two remaining species can also be readily differentiated from the new species: B. acollaris has more than two spines on the third exopodal segments of legs 2–4 (whereas the new species has only 2 spines), and a digitiform exopodal segment of leg 5 rather than a tapering segment as in B. iboensis sp. nov. Bonnierilla mollia has inflated exopods of legs 2–4 which are devoid of any spines, whereas the exopods of the new species are not inflated and all segments are armed with outer spines. These differences are sufficient to justify the establishment of the new species.