Cryptopontius aesthetascus, Neves, Elizabeth & Johnsson, Rodrigo, 2008

Neves, Elizabeth & Johnsson, Rodrigo, 2008, Three new species of Artotrogidae (Copepoda, Siphonostomatoida) from the southeastern coast of Pernambuco State, Brazil, Zootaxa 1932, pp. 47-60 : 52-56

Cryptopontius aesthetascus sp. nov.

( Figs 5–7 )

Material examined. Holotype ɗ ( MNRJ 12909) and 3 ɗ paratypes ( MNRJ 12920), ex sponges, Santo Aleixo Island, Serinhaem, Pernambuco, Brazil, leg. P.S. Young, 15 March, 1995.

Description of male. Mean body length (excluding caudal setae) 890 µm (875–904 µm), mean body width 460 Μm (452–475 µm) (based on 4 specimens). Body ( Fig. 5 a) cyclopiform, dorsoventrally flattened with moderately enlarged prosome, and cylindrical urosome. Pedigerous somite 1 totally fused with cephalosome; epimera of cephalothorax moderately pointed. Pedigerous somites 2 and 3 with pointed epimera. Pedigerous somites 4 and 5 concealed by third pedigerous somite. Prosome length:width ratio 1.4:1. Urosome composed of 6 somites (first urosomite excluded in Fig. 5 b). Genital somite 170 µm long, length:width ratio 0.6:1, rounded posteriorly. Four postgenital somites each wider than long (43 × 104 µm, 39 × 93 µm, 32 × 82 µm, 50 × 80 µm, respectively). Anal somite ( Fig. 6 a) with small lateral setule and spinules dorsally. Length ratio of prosome to urosome 2.7:1. Caudal rami ( Figs 5 b, 6a) elongate, 54 × 36 µm, armed with 6 setae (seta I absent); furnished with minute spinules on dorsal surface. Length of setae II–VII 32, 75, 237, 383, 105, and 62 µm, respectively; setae III–VI plumose, setae II and VII naked.

Antennule ( Fig. 5 c) slender, 269 µm long (not including setae), consisting of 12 segments, with ancestral segments III and IV partially fused. Length of segments: 82, 15, 28, 9, 8, 15, 13, 15, 13, 40, 23, and 52 µm, respectively. Setation as follows: 1, 1+ae, 4+2ae, 1+ae, 1+ae, 1+ae, 2+ae, 7+ae, 1+spine+ae, 4+2ae, 2+ae, 12+ae. Antenna ( Fig. 5 d) 123 µm long (including distal claw-like seta); basis 40 µm long. Exopod 1-segmented, 7 µm long, with 2 naked apical setae. Endopod 2-segmented; first segment 24 µm long, unarmed; second segment 35 µm long, furnished with 2 rows of setules and armed with proximomedial seta and 3 apical elements.

Oral cone ( Fig. 5 a) 320 µm long, reaching insertion of maxilliped. Mandibular palp absent; stylet ( Fig. 6 b) bears 7 subdistal teeth. Maxillule ( Fig. 6 c) bilobed; both lobes slender. Inner lobe 79 µm long, with setules along outer margin and 2 distal setae (1 unipinnate, 1 naked). Outer lobe 57 µm long, with short row of setules distally along inner margin and 2 long barbed setae. Maxilla ( Fig. 6 d) with 160 µm long syncoxa and 258 µm long claw; claw distally curved and armed with 2 setae, one medially and other subdistally near short row of setules. Maxilliped ( Fig. 6 e) 299 µm long, 5-segmented; syncoxa 28 µm long, with seta on inner margin; basis 159 µm long, with short seta on inner margin. Endopod 3-segmented; segments 55, 12 and 37 µm long, respectively. First segment armed with outer seta; second segment with distal seta; third segment with distal seta and slightly curved, 93 µm long claw. All maxillipedal setae naked.

P1-P3 ( Figs 7 a–c) biramous and trimerous. P4 ( Fig. 7 d) uniramous, without endopod. Armature formula for P1-P4 as follows:

Coxal seta and basis setae of P1 plumose; seta on coxa and basis of P2 and P3 naked; setae on rami plumose. Outer margin of P2–P4 exopod serrated. Distal spine on terminal exopodal segment of P2–P4 serrated along outer margin and setulate along inner margin.

P5 ( Fig. 7 e) comprised of protopodal segment fused to somite and free exopodal segment. Protopod with lateral naked seta. Exopod small, 21 µm long, with 3 distal naked setae. P6 ( Fig. 5 b) represented by 3 naked setae on posterior margin of genital somite.

Female. Unknown.

Etymology. The specific name “ aesthetascus ” alludes to the relatively high number of aesthetascs on the antennule.

Remarks. To date, all known Cryptopontius species have been described based on female specimens. The male sex, however, has also been described for all Cryptopontius species, except C. ricinius Malt, 1991 , C. graciloides Ummerkutty, 1961 , C. brevicaudatus (Brady, 1899) , C. proximus Nicholls, 1944 and C. paracapitalis ( Nicholls, 1944) . Nevertheless, the newly discovered male Cryptopontius species from Brazil is deemed to be an independent taxon, as it does not share a suite of important, non-sexually dimorphic features (i.e. segmentation of the antennule proximal to ancestral segments IX–XII, structure of the antenna and maxillulary endopod, and leg setation) with any known female congener.

Cryptopontius aesthetascus sp. nov. has an armature of III;4 on the third exopodal segment of P1, 2 inner setae and a total of 6 setae, respectively, on the second and third endopodal segments of P1, a total of 9 elements on the third exopodal segment of P4 and a uniramous P 4 in common with C. madeirensis Johnsson, 2001 , C. paracapitalis Nicholls, 1944 , C. capitalis (Giesbrecht, 1895) and C. thorelli (Giesbrecht, 1895) ( Giesbrecht 1899; Nicholls 1944; Johnsson 2001). However, C. aesthetascus sp. nov. can be easily distinguished from these four related taxa by having 7 expressed antennulary segments, rather than 3 ( C. madeirensis and C. paracapitalis ) or 4 ( C. capitalis and C. thorelli ), proximal to fused ancestral segments IX–XII (= expressed segment 8 in the new taxon).

Figures

FIGURE 5. Cryptopontius aesthetascus sp. nov., male holotype (MNRJ 12909). (a) habitus, dorsal; (b) urosomites 2 – 6, dorsal; (c) antennule; (d) antenna. Scale bars: a = 150 µm; b = 50 µm; c – d = 25 µm.

FIGURE 6. Cryptopontius aesthetascus sp. nov., male holotype (MNRJ 12909). (a) anal somite and caudal rami, dorsal; (b) distal end of mandibular stylet; (c) maxillule; (d) maxilla; (e) maxilliped. Scale bars: a, c – e = 25 µm; b = 50 µm.

FIGURE 7. Cryptopontius aesthetascus sp. nov., male holotype (MNRJ 12909). (a) P 1; (b) P 2; (c) P 3; (d) P 4; (e) P 5. Scale bars: all 25 µm.