Bonnierilla tahitiensis, 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 : 269-272

Bonnierilla tahitiensis sp. nov.

( Figs. 180 , 181 )

Typematerial. Holotype (intact ♀, MNHN-IU-2014- 21288 ) , paratypes (5 intact ♀♀, MNHN-IU-2014-21289), anddissectedparatype (♀, figured) from Herdmania momus (Savigny, 1816) , passe de Tapuaerha, Tahiti, depth 10-30 m, Monniot coll., June 1984.

Additionalmaterial. 7 ♀♀ (MNHN-IU-2018-1842) from H. momus, Moorea M 6, Tahiti; 7 ♀♀ (MNHN-IU-2018-1843) from H. momus, Moorea M 18, Tahiti; 1 ♀ (MNHN-IU-2018-1844) from H. momus, Moorea M 5, Tahiti; 1 ♀ (dissected, MNHN-IU-2015-14) from cyst of branchial tissue of Molgula pedunculata (Herdman, 1881) , Tahiti (17°52.65 Ś, 149°09.33 Ẃ), depth 6 m, 15 April 2013.

Etymology. The name of the new species is based on the type locality.

Description of female. Body ( Fig. 180A ) compressed, stout; length 2.25 mm. Prosome 1.68 mm long. Cephalosome clearly defined from unsegmented metasome. Fifth pedigerous somite fused with metasome. Freeurosome ( Fig. 180B ) 5-segmented: genitalsomite short, 91×353 μm; 4 abdominal somites becoming graduallyshorterandnarrowertowardsposterior,207×331, 153×295. 116×244, and 87×189 μm, respectively. Caudal ramus ( Fig. 180C ) elongate, curved, graduallynarrowing distally, about 4.0 times longer than wide (162×41 μm): armed with 5 naked setae (2 in middle and 3 distal) and 1 distal, flagellate claw (tipped with setule, see Fig. 180 D-F); ramus ornamented with numerous minute spinules on distal third of ventral surface; distal flagellate claw simple or bifid or trifid at its ventrodistal apex ( Fig. 180 D-F); 2 middle setae located at 50 and 62% of ramus length.

Rostrum nearly semicircular, 90×150 μm, similar to that of B. cheliphora sp. nov., indistinctly articulated from cephalosome. Antennule ( Fig. 180G ) 225 μm long, 8-segmented; armatureformula 3, 16, 11, 5, 4, 2, 2+aesthetasc, and 7+aesthetasc; first and second segments expanded; setae crowded and generally long, all setae naked. Antenna ( Fig. 180H ) slender, 4-segmented; coxa broad but unarmed; basis with 1 or 2 minute setal vestiges distally; first endopodal segment with 1 small seta subdistally; compound distal segment about 4.4 times longerthanwide (114×26 μm) and 1.5 timeslongerthan first; armed with 9 small setae plus small terminal claw, less than half length of segment.

Labrum( Fig.180I ) simplewithsetuloseposterolateral surfaces and slightly concave posterior margin. Mandible ( Fig. 180J ) with 5 teeth on coxal gnathobase; basis with 1 mediodistal seta; exopod 2-segmented, with 3 large setae on proximal segment and 2 shorter setae on small distal segment; endopod incompletely defined from basis, armed with 4 and 9 setae on first and second segments, respectively. Maxillule ( Fig. 180K ) with 10 setaeon arthrite, 1 broad, conical seta on coxal endite, 2 on epipodite, 3 on basis (proximal seta much smaller than distal 2), and 4 each onexopodand endopod. Maxilla ( Fig. 181A ) as usual, bearing 3 setae on first endite of syncoxa and 3 setae on third endopodal segment. Maxilliped ( Fig. 181B ) distinctly 2-segmentedwith 10 setaeonfirst segment and 2 subequal setae on second.

Legs 1–4 ( Fig. 181 C-F) with 3-segmented rami and similar to those of B. cheliphora sp. nov. Inner distal spine on basis of leg 1 extending beyond distal border of first endopodal segment, 47 μm long. Exopod 1.3 times longer than endopod in leg 1, 1.6 times longer in legs 2 and 3, and 1.5 times longer in leg 4. In legs 2–4, first exopodal segment longer than second and third exopodal segments combined, about 3.4 times longer than wide. Inner setae on exopods of legs 2–4 very small. Armature formula for legs 1–4 asin B. cheliphora sp. nov.

Leg 5 ( Fig. 181G ) 2-segmented; protopod short, with 1 seta at outer distal corner and several spinules near base of exopod; exopod about 4.7 times longer than wide (136×29 μm), tipped with 1 naked seta and ornamented with 5 rows of spinules on inner surface.

Male. Unknown.

Remarks. This new species very similar to B. cheliphora sp. nov. and occurs on one of the same host species, Herdmania momus . Both species have elongate, slightly curved caudal rami, an elongate exopod of leg 5, and possess a distal claw on the caudal ramus. However, the caudal claw is significantly different between these two species. The caudal claw of B. cheliphora sp. nov. is simple and conical, whereas in B. tahitiensis sp. nov. it is always flagellate (tipped with a setule) and may be distally bifid or trifid.

Figures

FIGURE 180. Bonnierilla tahitiensis sp. nov., female. A, habitus, right; B, urosome, ventral; C, caudal ramus; D–F, distal tip of caudal ramus showing 3 different forms of caudal claws, 3 distal setae omitted; G, antennule; H, antenna; I, labrum; J, mandible; K, maxillule. Scale bars: A, 0.5 mm; B, 0.1 mm; C, G–K, 0.05 mm; D–F, 0.01 mm.

FIGURE 181. Bonnierilla tahitiensis sp. nov., female. A, maxilla; B, maxilliped; C, leg 1; D, leg 2; E, leg 3; F, leg 4; G, leg 5. Scale bars: 0.05 mm.