Oncaea media, Giesbrecht, 1891

Juan M. Fuentes-Reinés & Eduardo Suárez-Morales, 2017, New records of poecilostomatoid copepods (Crustacea) from a coastal system in the Colombian Caribbean with notes on morphology, Check List 13 (5), pp. 513-523 : 516-517

media

Material examined. Ten adult females, undissected, 2 dissected ( UARC 285M).

Remarks. The body is cyclopiform, robust, habitus as in Figure 6. Body length, excluding caudal setae = 532–588 µm, average: 562 µm (n = 10). This species was originally described by Heron and Bradford-Grieve (1995) from the Gulf of Naples and redescribed by Böttger-Schnack (2001) based on specimens from the Gulf of Naples, the Red Sea, and the Gulf of Aden. It can be found in the epimesopelagic layer ( Böttger-Schnack 2001) and our data shows its occurrence in shallow littoral areas, as observed for O. venusta .

The specimens from Colombia have the diagnostic features of O. scottodicarloi as described by Heron and Bradford-Grieve (1995) and Böttger-Schnack (2001). There are, however, some subtle differences in our speci- mens: 1) length/width ratio of genital double-somite is 1.5 in populations from the Red Sea and Gulf of Aden ( Böttger-Schnack 2001, fig. 22A, C), 1.4 in those from the Gulf of Naples ( Heron and Bradford-Grieve 1995, fig. 17K) and this ratio is somewhat smaller (1.27) in the Colombian specimens (Fig. 7); 2) the length ratio of the genital double-somite with respect to the rest of urosomites is 2.5 in Red Sea and Gulf of Aden specimens ( Böttger-Schnack 2001, figs 22A,C), 2.3 (Gulf of Naples) ( Heron and Bradford-Grieve 1995, fig. 17K), and 2.2 in the Colombian specimens (Fig. 7). Overall, these differ- ences are deemed to be intraspecific variations and thus expand the knowledge on the morphometric variability of this species.

In the Americas, this species can be confused with O. media Giesbrecht, 1891 and O. waldemari Bersano & Boxshall 1996 but they can be distinguished by several characters: 1) the length/ width ratio of the genital double-somite is about 1.27–1.50 in O. scottodicarloi ( Heron and Bradford-Grieve 1995, fig. 17K; present data, Fig. 7), 1.7 in O. waldemari ( Böttger-Schnack 2001, fig. 24C), and 1.9 in O. media ( Heron and Bradford-Grieve 1995, fig. 16A; Böttger-Schnack 2001, fig. 15C), 2) the length ratio genital double-somite/ rest of urosomites is 2.2–2.5 in O. scottodicarloi ( Heron and Bradford-Grieve 1995, fig. 17K; Böttger-Schnack 2001, fig. 22A, C; present data, Fig. 7), 1.9 in O. waldemari ( Böttger-Schnack 2001, table 1), and 3.9 in O. media ( Heron and Bradford-Grieve 1995, fig. 16A; Böttger-Schnack 2001, fig. 15A, C), 3) the shape and location of the sclerotization differs among these species, in O. scottodicarloi , it is a line connected to the genital aperture ( Heron and Bradford-Grieve 1995, fig. 17K; Böttger-Schnack 2001, fig. 22 C; Wi et al. 2009, fig. 10A; present data, Fig. 8), whereas in both O. media and O. waldemari sclerotization is absent ( Heron and Bradford-Grieve 1995, fig. 16A; Böttger-Schnack 2001, fig. 15C, Wi et al. 2009, figs 8A, 11A).

Distribution. It has been recorded in the Indian, Atlantic, and Pacific Oceans ( Heron and Bradford-Grieve 1995, Böttger-Schnack 2001). This is the first record of this species in Colombian waters and in the Caribbean.

Family Lubbockiidae Huys & Böttger-Schnack, 1997 Genus Lubbockia Claus, 1863