Notopterophoroides quadridentatum, 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 : 179-182

Notopterophoroides quadridentatum sp. nov.

( Figs. 117 , 118 )

Type mataerial. Holotype (intact ♂, MNHN-IU-2014- 21254 ) and paratype (♂, dissected and figured) from Phallusia arabica Savigny, 1816 (MNHN-IT-2008-6109 = MNHN P5/ PHA /75), MUA 3, Nosy Be, Madagascar, P. Laboute coll.

Etymology. The specific name quadridentatum refers to the presence of four teeth on the mandibular gnathobase.

Descriptionofmale. Body ( Fig. 117A ) moderately narrow, slightly compressed. Bodylength 1.34 mm: prosome 854 μm long, tapering anteriorly in lateral view, obscurely segmented by weak constrictions and wrinkles between somites. Dorsoventral depth of prosome 340 μm. Dorsal cephalothoracic shield distinct. Fifth pedigerous somite fused with fourth. Free urosome distinctly 5- segmented. Anal somite ( Fig. 117B, C ) short, half as long as wide, protruding posteroventrally, ornamented with scattered spinules on ventral surface; anal operculum discernible. Caudalramus ( Fig. 117B ) small, about 1.3 times longer than wide (32×25 μm), armed with 3 claws and 3 setae ( Fig. 117C ) and ornamented with spinules scattered over all surfaces; lengths of claws 22, 20, and 12 μm; all shorter than ramus. Spermatophore ( Fig. 117D ) 75×32 μm, with thick wall and short tube.

Rostrum ( Fig. 117E ) widerthan long, 65×125 μm, nearly semicircular. Antennule ( Fig. 117F ) short, 117 μmlong, and 7-segmented; armatureformula 7, 13, 12+aesthetasc, 6, 6, 4+aesthetasc, and 5+aesthetasc; setae extremely crowded, all naked. Antenna ( Fig. 117G ) 4- segmented; coxa short; basis slightly longer than wide, with pinnate exopodal seta and several small spinules on inner margin; first endopodal segment longer than basis, with 1 naked seta subdistally on outer margin; compound distal endopodal segment about 3.1 times longer than wide (47×15 μm), ornamented with spinules on outer and inner margins; armedwith 9 setae (including 3 bluntly tipped) plus terminal claw about half as long as segment.

Labrum ( Fig. 117H ) with large posteromedianlobe bearing setules on posterolateral surfaces. Mandibular coxalgnathobase ( Fig. 117I ) with 4 teeth, 2 smallproximal setae, and 2 needle-like spinules between second and third teeth: basis of mandible with small mediodistal seta ( Fig. 117J ): exopod 2-segmentedwith 3 and 2 setaeon first and second segments, respectively; terminal seta on second segment about 0.7 times as long as other 4 setae: endopod with 4 and 9 setaeon first and second segments, respectively; apical seta on second endopodal segment enlarged. Maxillule ( Fig. 117K ) with 9 setaeon arthrite, 1 on coxal endite, 2 on epipodite, 3 on basis, 3 on exopod and 4 on endopod. Maxilla ( Fig. 117L ) 5-segmented; syncoxa with 3 (including small naked seta), 1, 2, and 2 setae on first to fourth endites, respectively; basis with 2 setae; endopod with 1, 1, and 3 setae on first to third segments, respectively. Maxilliped ( Fig. 118A ) distinctly 2-segmented with 9 (4+5) medial setae on first segment and 2 apical setae on second.

Legs 1–4 ( Fig. 118 B-E) with 3-segmented rami. Inner coxal seta absent on legs 1–4. Inner distal spine on basis of leg 1 slightly longer than first endopodal segment, straight and spinulose. Third exopodal segment of leg 1 bearing small seta as proximalmost outer element. Second endopodal segment bearing 1 inner seta in legs 1 and 4, but with 2 inner setae in legs 2 and 3. Armature formula for legs 1–4 as follows:

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

Leg 5 ( Fig. 118F ) consisting of short protopod and small free exopod; left and right protopods fused to form protopodal plate bearing pinnate seta at each outer corner ornamented with few inner spinules: exopodal segment suboval, slightly longer than wide (18×16 μm) with 1 pinnate seta on apex and 3 small sensillae on ventral surface. Leg 6 ( Fig. 118F ) represented by 2 pinnate setae on distal margin of genital operculum.

Female. Unknown,

Remarks. Speciesof the genus Notopterophoroides seem to exhibit very little sexual dimorphism, as indicated by N. armadillo redescribed above. This weak sexual dimorphism allows us to describe N. quadridentatum sp. nov. on the basis of the male, since robust comparisons can still be made with its other congeners.

The most remarkable feature of the new species is the 3-segmented endopod of leg 1. Within the genus this feature is shared only with N. malacodermatus , which Schellenberg (1922) described very imperfectly, illustrating only the exopod of leg 3 and leg 5. His figured leg 5 is somewhat similar to that of N. quadridentatum sp. nov., but the protopodal seta is longer than the apical seta on the exopod, the exopod of leg 3 lacks an inner seta on the first segment, and the outer spines on the exopod are very short. These differences are sufficient to distinguish N. quadridentatums sp. nov. from other congeneric species.

Figures

FIGURE 117. Notopterophoroides quadridentatum sp. nov., female. A, habitus, right; B, anal somite and caudal ramus, left; C, anal somite and caudal rami, ventral; D, spermatophore; E, rostrum; F, antennule; G, antenna; H, labrum; I, coxal gnathobase of mandible; J, mandibular palp; K, maxillule; L, maxilla. Scale bars: A, 0.1 mm; B-D, F-L, 0.02 mm; E, 0.05 mm.

FIGURE 118. Notopterophoroides quadridentatum sp. nov., female. A, maxilliped; B, leg 1; C, leg 2; D, exopod of leg 3; E, leg 4; F, legs 5 and 6. Scale bars: 0.02 mm.