Halicyclops A. M. Norman, 1903

Gómez, S. & Rocha, C. E. F., 2005, A new species of Kristensenia Por, 1983 and a new record and illustrated supplementary description of Halicyclops hurlberti Rocha, 1991 from Mexico, Journal of Natural History 39 (2), pp. 133-152 : 144

Genus Halicyclops A. M. Norman, 1903

Halicyclops hurlberti Rocha, 1991 ( Figures 8–14 )

Distribution. USA: Tihuana estuary, California ( Rocha 1991); Mexico: Sinaloa, northwestern Mexico (present study).

Citations. Rocha (1991).

Taxonomic remarks

In the original description of H. hurlberti, Rocha (1991) allocated the species to a group defined by the ornamentation of seta V of the caudal rami, size of the female fourth antennular segment and size of the inner spine of the basis of P1. On the other hand, Rocha (1991) defined H. hurlberti by the size and shape of the inner distal seta of P4 endopod 3, shape and size of the P5 exopod, and relative length and separation between the setae of the same leg. The specimens found in sediment samples from Ensenada del Pabellón lagoon and Urías system are identical to H. hurlberti as described by Rocha (1991) based on the characteristics listed above ( Figures 8A–C , 11A, B , 12A, B , 13A, B ). In the original description, Rocha (1991) gave only the armature formula of the female antennule and omitted the description of mouthparts since they are ‘as those of Halicyclops glaber Rocha 1983 ’. We include the complete illustration of female A1 ( Figure 11A ), A2 ( Figure 9A ), Md, Mxl, Mx, Mxp ( Figure 10A–I ) and labrum ( Figure 9B ), as well as of male A1 ( Figure 14 ), P5, P6 and abdomen ( Figure 13A, B ). This new record extends the distribution of the species from temperate southern California to the subtropical eastern Pacific.

Figures

Figure 8. Halicyclops hurlberti Rocha 1991, female. (A) Urosome, dorsal; (B) caudal setae IV and V; (C) anal somite and right caudal ramus, dorsal. Scale bar: 100 Mm (A); 143 Mm (B); 50 Mm (C).

Figure 9. Halicyclops hurlberti Rocha 1991, female. (A) Antenna; (B) labrum. Scale bar: 60 Mm.

Figure 10. Halicyclops hurlberti Rocha 1991, female. (A) Mandible; (B) biting edge of mandibular gnathobase; (C) maxillule; (D) maxillulary palp showing armature of basis, endopod and exopod; (E) arthrite of maxillulary praecoxa; (F) maxilla; (G) maxillary allobasis and endopod; (H) maxillary coxal endite; (I) maxilliped. Scale bar: 70 Mm (A, I); 47 Mm (B); 100 Mm (C, F); 67 Mm (D, E, G, H).

Figure 11. Halicyclops hurlberti Rocha 1991, female. (A) Antennule, disarticulated; (B) P1. Scale bar: 100 Mm.

Figure 12. Halicyclops hurlberti Rocha 1991, female. (A) P4; (B) P5. Scale bar: 71 Mm (A); 50 Mm (B).

Figure 13. Halicyclops hurlberti Rocha 1991, male. (A) Urosome, ventral; (B) P5. Scale bar: 100 Mm (A); 60 Mm (B).

Figure 14. Halicyclops hurlberti Rocha 1991, male. (A) Antennule; (B) segment VI–XII of A1; (C) segment XI–XII of A1. Scale bar: 50 Mm (A); 63 Mm (B); 33 Mm (C).