Bradypontius ancistronus sp. nov.

(Figs 2–4)

Material examined. Holotype ɗ (MNRJ 12910) and 5 ɗ paratypes (MNRJ 12916), ex sponges, Santo Aleixo Island, Serinhaem, Pernambuco, Brazil, leg. P.S. Young, 15 March, 1995.

Description of male. Mean body length (excluding caudal setae) 933 µm (925–941 µm), mean body width 416 µm (402–425 µm) (based on 6 specimens). Body (Fig. 2 a) cyclopiform, dorsoventrally flattened, with moderately enlarged prosome, and cylindrical urosome. Pedigerous somite 1 completely fused with cephalosome; cephalothorax with rounded epimera. Pedigerous somites 2–4 with pointed epimera. Pedigerous somite 3 extends over two succeeding pedigers and proximal one-third of genital somite. Prosome length:width ratio 1.8:1. Urosome (Fig. 2 b) composed of 6 somites. Genital somite 171 µm long, length:width ratio 0.5:1, rounded anterolaterally. Four postgenital somites each wider than long (61 × 102 µm, 48 × 87 µm, 39 × 80 µm, 59 × 87 µm, respectively). Prosome:urosome length ratio 2.2:1. Caudal rami subrectangular, 42 × 37 µm, armed with 6 setae (seta I absent). Setae II–VII 29, 120, 354, 566, 186, and 32 µm long, respectively; setae III to VI plumose, setae II and VII naked.

Antennule (Fig. 2 c) 258 µm long (not including setae), comprised of 9 segments. Length of segments: 67, 48, 13, 11, 9, 13, 38, 15, and 43 µm, respectively. Setation as follows: 1, 5, 1, 2, 2, 6, 2+spine, 1, 9+ae. Aesthetasc 191 Μm long. Antenna (Fig. 2 d) 153 µm long (including distal claw); basis 35 µm long. Exopod 1-segmented, 7 µm long, with 2 apical naked setae. Endopod 2-segmented; first segment 27 µm long, unarmed; second segment 31 µm long, with 3 naked elements (proximomedial seta, apical seta and straight terminal claw).

Oral cone (Fig. 2 a) 366 µm, reaching insertion of P1. Mandibular palp absent; mandibular stylet (Fig. 3 a) long, stout, armed with 6 distal teeth. Maxillule (Fig. 3 b) bilobed; both lobes stout. Inner lobe 51 µm long, with setules along inner margin and 3 distal setae (1 naked, 1 plumose, 1 unipinnate). Outer lobe 45 µm long, with 2 apical naked setae. Maxilla (Fig. 3 c) with 180 µm long syncoxa and 307 µm long claw; claw distally curved, with seta and patches of setules subapically. Maxilliped (Fig. 3 d) 4-segmented, 540 µm long; syncoxa 78 µm long, with small inner seta; basis 222 µm long, with short subdistal seta on inner margin. Endopod 2- segmented, 76 and 47 µm long, respectively; first segment with naked distal seta; second segment bears naked distal seta and 116 µm long, distally curved, claw-like element.

P1-P4 (Figs 3 e–f, 4a–b) biramous, 3-segmented. Armature formula of P1-P4 as follows:

Distal exopodal spine of P2 and P4 heterogeneously ornamented, with serrate outer margin and setulate inner margin. Coxal seta of P1 and P3 plumose; basal seta of P1–P3 naked. Exopodal spines of P1 smaller than those of P2–P4. Outer margin of first exopodal segment of P1–P3 and second exopodal segment of P2 covered with setules. P4 with unarmed endopod; third segment with distal hook-like projection. P5 (Fig. 2 b) comprised of protopodal segment fused to somite and free exopodal segment. Protopod with seta near insertion of exopod. Exopod small, 16 µm long, with 3 distal naked setae. P6 (Fig. 2 b) represented by 1 plumose and 2 naked setae on posterolateral margin of genital somite.

Female. Unknown.

Etymology. The specific name refers to the the Greek word “ ankistron” which means fish hook, alluding to the hook-like projection on the third endopodal segment of P4.

Remarks. Bradypontius ancistronus sp. nov. possesses two apomorphic characteristics not found in any other known male congener. Firstly, the third exopodal segment of P 1 in B. ancistronus sp. nov. has 2 outer spines rather than 3 as in all other species of the genus. Secondly, the P4 endopod of the new species is totally unarmed, with the third segment bearing a distal hook-like process. Only B. serratipes Nicholls, 1944, B. ovatus Nicholls, 1944, B. inermis Nicholls, 1944 and B. pichoni Stock, 1966 have the first two endopodal segments of P4 unarmed as in the new species; however, the third segment bears at least 1 seta in these four nominal species (Nicholls 1944; Stock 1966). Although it seems reasonable to erect a new genus for this Brazilian species based on the two aforementioned apomorphic features, we believe it is more appropriate to retain the new species in Bradypontius pending the collection of female specimens of the new taxon.