Acartia (Odontacartia) bispinosa Carl, 1907

El-Sherbiny, Mohsen M. & Al-Aidaroos, Ali M., 2014, First report of the presence of Acartiabispinosa Carl, 1907 (Copepoda, Calanoida) in a semi-enclosed Bay (Sharm El-Maya), northern Red Sea with some notes on its seasonal variation in abundance and body size, ZooKeys 444, pp. 95-118 : 96-99

Taxon classification Animalia Calanoida Acartiidae

Acartia (Odontacartia) bispinosa Carl, 1907

Acartia amboinensis (F): Sewell 1914 a (p. 242, figs 1-7 Only female)

Acartia tokiokai Mori 1942 (p. 556, pl. 11, figs 1-18)

Acartia hamata C.B. Wilson 1950 (p. 152, figs 1-5)

Description.

Female: Body (Fig. 1A, B) slender; prosome 5-segmented; rostrum (Fig. 1C) with two long rostral filaments and paired frontal sensilla (Figs 1C, 2A). Nauplius eye present. Cephalosome and first pediger completely separate; fourth and fifth pediger fused; fifth pediger with lateral strong projection, posterodorsal spine and fine setule on each side (Fig. 1A, F–G). Urosome 3-segmented; genital compound somite (Fig. 1 D–G) slightly longer than wide, carrying two spines postero-dorsally reaching nearly one-third of second urosomite, posteroventral margin furnished with very fine hairs (Figs 1E, 2B); second and third segments naked. Caudal rami symmetrical; with 5 transverse rows of fine setules dorsally and 1 row anteroventrally (Fig. 1 D–E), each ramus bearing six setae.

Antennule (Fig. 1H, I): incompletely 19-segmented; second to third and fourth to sixth segments partly fused on dorsal surface; segmentation and setation patterns as follows (SS specialized spine): (1) I=1+2SS, (2) II–VI =6+SS+1 aesthetasc (ae), (3) VII–VIII =2, (4) IX–X =2 (1 spiniform), (5) XI–XII =2+ae, (6) XIII=1, (7) XIV–XV =3+ae, (8) XVI=1+ae, (9) XVII=1, (10) XVIII=1+ae, (11) XIX=1, (12) XX=1, (13) XXI=1+ae, (14) XXII=1, (15) XXIII=1, (16) XXIV=1+1, (17) XXV=1+1+ae, (18) XXVI=1+1, (19) XXVII–XXVIII =4+ae. First segment with short spine at distal half and 2-3 spinules on dorsal surface; second segment with strong claw-like spine curved proximally from mid-posterior margin (Figs 1C, 2C), transverse row of 2-3 spinules on proximal half of dorsal surface and transverse row of 4 spinules on distal half of dorsal surface; fourth segment with 2 spines dorsally.

Antenna (Fig. 3A) long; coxa with one seta; basis and first endopodal segment completely fused forming elongate allobasis carrying 9 setae along medial margin and oblique row of tiny spinules on distal part of anterior surface; exopod short, 4-segmented with setal formula of 1, 2, 2, 3. Second (first free) endopodal segment elongated bearing 7 setae and furnished with hairs along lateral margin; third (second free) endopodal segment short bearing 7 setae.

Mandible (Fig. 3B): coxa with well-developed gnathobase; basis with 1 medial seta and group of fine spinules posteriorly; exopod 5-segmented, with setal formula of 1, 1, 1, 1, 2; endopod 2- segments, with 2 and 9 setae on first and second segment respectively.

Maxillule (Fig. 3C): praecoxa and coxa incompletely fused; praecoxal arthrite (endite) with 9 setae; coxal endite with 3 setae, coxal exite bearing 9 setae; basis with thick medial seta and short lateral seta; exopod 1-segmented and bearing 2 setae laterally and 5 setae terminally; endopod absent.

Maxilla (Fig. 3D): precoxa and coxa incompletely fused; with 4 endites, each carrying short seta on each and 3, 1, 1, 2 long setae, respectively; basis with 1 long seta and 1 short seta; endopod 4-segmented, with 5 long setae, 2 medium setae and 1 short seta.

Maxilliped (Fig. 3E) comprising robust syncoxa, basis, and 2-segmented endopod; syncoxal endite with 6 setae (2 short, 2 medium and 2 long); basis bearing 1 short spiniform seta; endopod 2-segments, first segment with 3 medial spine-like setae, second segment tapered at end carrying 2 setae (later one spiniform and elongated at tip).

Swimming legs 1 to 4 (Fig. 3 F–I) biramous, with 3-segmented exopod and 2-segmented endopod; third exopodal segment of leg 1 with 4-5 spinules proximally on the ventral surface(Fig. 3J); second endopodal segment of leg 3 with group of tiny spinules proximally on the ventral surface (Fig. 3K); basis of leg 4 with 4 spinules ventrally (Fig. 3L). Seta and spine formula as follows:

Leg 5 (Fig. 3M): coxae completely fused to intercoxal sclerite; basis about 1.5 times longer than wide; lateral seta nearly as long as claw-like exopod; exopod reduced and swollen at the base posteriorly and distal two-third furnished medially with very fine spinules (Fig. 2D).

Male: Body (Fig. 4A) slender; rostral filaments long and thin (Fig. 4B). Fifth pediger with 2 subequal pointed posterior processes, smaller than in female, 2 dorsolateral spines and fine setules on each side (Fig. 4C, D). First urosomite with rows of soft hairs on lateral and posterior margin (Fig. 4C, D). Second urosomite with 2 strong dorsolateral spines on posterior margin reaching slightly more than two-thirds of the following somite, 2 ventrolateral small spines, 2 dorsolateral groups of fine spinules ventrolaterally on both sides and dorsolateral row of fine setules along posterior margin (Figs 4C, D, 5A). Third and fourth urosomites with very fine setules along posterior margins. Anal somite bearing short hairs on lateral surface. Caudal ramus with transverse rows of fine setules at the base of medial dorsal seta and with hairs along lateral margin and along distal half of medial margin.

Left antennule (Fig. 4E) 21-segmented; segmentation and setation patterns as follows: (1) I=1, (2) II–IV =3, (3) V–IX =4+ae, (4) X=2+ae, (5) XI=2+ae, (6) XII=unarmed, (7) XIII=unarmed, (8) XIV=2 (1 spiniform)+ae, (9) XV=1+ae, (10) XVI=1+ae, (11) XVII=1, (12) XVIII=1, (13) XIX=1, (14) XX=1, (15) XXI=1+ae, (16) XXII=1, (17) XXIII=1, (18) XXIV=1+1, (19) XXV=1+1+ae, (20) XXVI=1+1, (21) XXVII–XXVIII =4+ae.

Right antennule (Fig. 4F) 17-segmented, with geniculation between thirteenth and fourteen segments; second to fourth segments partly fused on dorsal surface; segmentation and setation patterns as follows: (1) I=2, (2) II–VI =3, (3) VII–VIII =3+ae, (4) IX–XI =4 (1 spiniform)+ae, (5) XII=unarmed, (6) XIII=unarmed,(7) XIV=2 (1 spiniform)+ae, (8) XV=1+ae, (9) XVI=1+ae, (10) XVII=1, (11) XVIII=1+ae, (12) XIX=1, (13) XX=1, (14) XXI–XXIII =2+process, (15) XXIV–XXV =2+2+ae, (16)XXVI=1+1, (17) XXVII–XXVIII =4+ae. Ninth segment covered with tiny spinules on the dorsal surface.

Other mouthparts and leg 1 to leg 4 as in female. Male leg 5 (Figs 4G, 5B) asymmetrical; intercoxal sclerite completely fused to both coxae. Left leg 5 basis nearly two times longer than wide and armed with long later seta; exopod 2-segmented; proximal exopodal segment shorter than distal exopodal segment carrying one seta distally; distal exopodal segment carrying 2 terminal spines, a stout spine at mid-anterior surface with fine setae near its base, 5 groups of very tiny spinules along medial margin, and several spinules along lateral margin (Fig. 4H). Right leg 5 comprising basis armed with lateral seta and 3-segmented exopod; first exopodal segment with 1 long seta; second exopodal segment with distal projection carrying 1 small spine medially and 2 groups of fine spinules on the posterior surface; third exopodal segment armed with terminal stout spine and 1 spine medially near distal end (Fig. 4I).