Acuticoxa ubatubaensis, Huys, Rony & Kihara, Terue Cristina, 2010

Huys, Rony & Kihara, Terue Cristina, 2010, Systematics and phylogeny of Cristacoxidae (Copepoda, Harpacticoida): a review, Zootaxa 2568, pp. 1-38 : 22-27

Acuticoxa ubatubaensis sp. nov.

Type locality. Brazil, São Paulo State, Ubatuba (23º31.2’ S, 44º51.0’ W); 44 m depth, medium coarse sand.

Type material. Holotype Ƥ dissected on 8 slides (reg. no MZUSP 19626). Collected in March 1989 by T. Corbisier.

Description. FEMALE ( Figs 14–17 ). Total body length 568 μm. Largest width measured at posterior margin of P2-bearing somite (102 μm). Body ( Fig. 14 A) cylindrical and elongate, slightly flattened dorsoventrally, without deep constrictions between somites. Urosome slightly narrower than prosome.

Rostrum ( Figs 14 A; 15C) well developed, triangular, with acuminate tip; completely defined at base; with pair of dorsal sensillae at about halfway its length; dorsal surface covered by small setules/spinules.

Cephalothorax rectangular, anterior margin with rounded, lobate extensions either side of rostrum; moderately produced ventrally; ornamentation consisting of sensillae and pores as illustrated in figure 14A; posterior margin smooth. Pedigerous somites ( Fig. 14 A) densely covered with rows of setules and with sensillae and pores as illustrated; posterior margin finely spinulose. Urosome ( Fig. 14 A–C) 5-segmented, comprising P5-bearing somite, genital double-somite, 2 free abdominal somites and anal somite. Urosomites with surface ornamentation consisting of rows of setules, sensillae and minute spinules ( Fig. 14 A–C); posterior margin of P5-bearing somite finely spinulose, genital double somite to penultimate somite with incised subulate hyaline frill ( Fig. 14 B–C). Genital double-somite ( Fig. 14 B–C) completely fused dorsally and ventrally; ventrally with minute spinules anterior to genital field and with transverse setular rows in posterior half ( Fig. 14 C–D); large copulatory pore located in midventral depression ( Fig. 14 C–D); gonopores fused medially, forming single genital slit covered on both sides by opercula derived from sixth legs. P6 with small protuberance bearing 2 naked setae, innermost longest. Anal somite ( Figs 14 B–C; 15A) with moderately developed, rounded, spinulose anal operculum; surface ornamentation consisting of setules and a pair of pores dorsally; anal opening with fringe of fine setules; posterior margin of somite serrate dorsally ( Fig. 15 A) and smooth ventrally ( Fig. 14 C).

Caudal rami ( Fig. 15 A–B) elongate, 3.6 times as long as maximum width; with inner bulge halfway the ramus length and tapering posteriorly. Each ramus with 2 lateral tube-pores near outer margin, surface ornamentation consisting of irregular pattern of striations, and 7 setae: seta I naked, vestigial and closely set to naked seta II; seta III naked and displaced to ventrolateral position; seta IV naked; seta V short and stubby, less than one third the length of the ramus (but setular distal part probably broken off; cf. condition in A. biarticulata ); setae IV and V not fused basally; seta VI naked; seta VII incomplete on both sides but triarticulate at base.

Antennule ( Fig. 15 D) 4-segmented, arising from subcylindrical pedestal, with segments III–IV oriented posteriorly. Segment I very long, with 1 small naked seta; segment III with aesthetasc fused basally to seta and arising from distinct setophore; segment IV tapering distally. Armature formula: I-[1], II-[7 + 1 pinnate], III- [8 + (1 + ae)], IV-[10 + acrothek]. Acrothek reduced, consisting of fused seta and aesthetasc.

Antenna ( Fig. 15 E) 3-segmented, comprising coxa, allobasis and free 1-segmented endopod. Coxa small, with no ornamentation. Basis and proximal endopod segment fused, forming elongate allobasis; with small naked abexopodal seta. Exopod completely absent. Free endopod slightly shorter than allobasis; medial armature consisting of 2 widely separated spines; apical armature consisting of 2 spines and 3 geniculate setae, outermost one of which fused basally to short seta and surrounded at base by few short spinules.

Mandible ( Fig. 16 A) with well-developed, elongate gnathobase bearing several multicuspidate teeth and 1 pinnate seta along distal margin. Palp biramous with incorporated exopod and discrete endopod; basis with 2 setae near distal margin (1 naked seta set on a conical protuberance and 1 long pinnate seta); exopod represented by a naked seta arising from proximal half of basis (indicated by asterisk in Fig, 16A); endopod short, about ¼ the length of basis, with about 3 apical setae.

Maxillule ( Fig. 16 B–C). Arthrite well developed, with 6 spines/setae around distal margin ( Fig. 16 C) and 1 naked seta subapically on both anterior and posterior surface. Coxa with cylindrical endite bearing 2 naked setae. Basis with 2 endites; proximal one with 2 naked setae; distal one with 3 naked setae. Endopod incorporated into basis, represented by 2 naked setae. Exopod absent.

Maxilla ( Fig. 16 D–E) with 2 endites on syncoxa. Praecoxal endite absent. Proximal coxal endite with 1 pinnate spine and 1 spine with swollen spinulose tip ( Fig. 16 E). Distal coxal endite with 3 naked setae. Allobasis drawn out into strong claw showing pore along outer margin and accompanying naked seta along inner margin. Endopod incorporated into basis and represented by 2 naked setae.

Maxilliped ( Fig. 16 F) elongate, arising from short pedestal. Syncoxa and basis unarmed. Endopod drawn out into long and geniculate claw; accompanying armature consisting of 1 naked seta.

P1 ( Fig. 17 A) prehensile. Coxa with outer margin forming large unguiform projection. Basis with 1 pore on anterior surface, 1 pinnate seta on outer distal corner and 1 small naked seta along inner margin. Exopod 2- segmented; exp-1 with row of spinules along distal margin and 1 pinnate outer seta; exp-2 with 3 lateral and 2 apical pinnate setae. Pinnules on outer basal seta and exopodal setae long and fine. Endopod 2-segmented, twice longer than exopod; enp-1 at least 4.3 times longer than enp-2, with few spinules along inner margin and cuticular reinforcement near distal margin; enp-2 with few spinules near inner distal corner, 1 claw and 1 long seta with reinforced basal part and setular distal part.

P2–P4 ( Fig. 17 B–D) small with reduced segmentation. Coxae with outer margin forming a pointed projection, smooth in P2–P3, fringed with small spinules in P4. Bases with outer corner produced into long setophore bearing pinnate (P2) or naked (P4) seta (lost in P3); with 1 large pore on anterior surface and row of spinules at inner corner (in P3–P4 only). Exopods 1-segmented, with spinules along outer and distal margins (except P4); original segmentation of P2 exopod indicated by transverse row of long spinules; all elements bipinnate and spiniform except for distal outer element on P3–P4 being naked and setiform. Endopods 1- segmented, small; with rows of spinules along inner and outer margins; with 1 naked (P2), plumose (P3) or pinnate (P4) seta apically. Armature formula as follows:

Exopod Endopod

P1 0.023 0.020

P2 0 23 0 10

P3 0 23 0 10

P4 0 23 0 10

P5 ( Fig. 17 E) with baseoendopod and exopod fused, forming single plate; not fused to supporting somite; narrow intercoxal plate discernible; anterior surface with 4 secretory pores and densely covered with minute setules; with 8 elements, including 3 pinnate spines, 4 plumose setae and one of unconfirmed shape and size (missing on both sides in holotype; insertion site arrowed in Fig. 17 E).

MALE. Unknown.

Etymology. The new species is named after the Ubatuba municipality where the type locality is situated.

Figures

FIGURE 14. Acuticoxa ubatubaensis gen. et sp. nov. (Ƥ): (A) habitus, dorsal; (B) urosome, dorsal [segment bearing P 5 omitted]; (C) urosome, ventral [segment bearing P 5 omitted]; (D) genital field. Scale bars: 25 μm.

FIGURE 15. Acuticoxa ubatubaensis gen. et sp. nov. (Ƥ): (A) anal somite and left caudal ramus, dorsal; (B) left caudal ramus, ventral; (C) rostrum, dorsal; (D) antennule, ventral; (E) antenna. Scale bars: 12.5 μm.

FIGURE 16. Acuticoxa ubatubaensis gen. et sp. nov. (Ƥ): (A) mandible [asterisk indicating exopodal seta]; (B) maxillule; (C) maxillule, disarticulated; (D) maxilla; (E) maxilla, disarticulated; (F) maxilliped. Scale bars: 12.5 μm.

FIGURE 17. Acuticoxa ubatubaensis gen. et sp. nov. (Ƥ): (A) P 1, anterior; (B) P 2, anterior; (C) P 3, anterior [arrow showing insertion site of dislodged outer seta]; (D) P 4, anterior; (E) P 5, anterior [arrows showing insertion sites of missing seta]. Scale bars: 12.5 μm.