Cymbasoma guerrerense, Suárez-Morales & Morales-Ramírez, 2009

Suárez-Morales, Eduardo & Morales-Ramírez, Alvaro, 2009, New species of Monstrilloida (Crustacea: Copepoda) from the Eastern Tropical Pacific, Journal of Natural History (J. Nat. Hist.) 43 (21 - 22), pp. 1257-1271 : 1264-1265

Cymbasoma guerrerense sp. nov.

Cymbasoma tumorifrons Isaac ; Suárez-Morales and Alvarez-Silva 2001

Material examined

Holotype. Adult female from Zihuatanejo Bay, central coast of the Mexican Pacific, coll. 14 September 1999, vial deposited at ECOSUR (ECO-CHZ-01127). Two adult females of C. tumorifrons , allotype and paratype, from Emborios Bay, Aegean Sea, Greece, deposited in the Natural History Museum, London (1974.407.12, 408.12). One adult female of C. tumorifrons from Toulon Bay, France, specimen deposited at ECOSUR (ECO-CHZ-01128).

Type locality

Bahía de Zihuatanejo (17°38′00′′ N, 101°33′30′′ W), state of Guerrero, on the central coast of the Mexican Pacific.

Diagnosis

This species was described and depicted by Suárez-Morales and Alvarez-Silva (2001), including full details of the antennular elements following Grygier and Ohtsuka (1995). Females of this species with robust cephalothorax 2.7 times longer than wide and representing 55% of total body length, and short antennules equalling 14.5% of body length. Forehead moderately protuberant and corrugated. Fifth legs widely divergent, with single lobe armed with three distal setae, innermost being shorter and thinner than the others. Lobe with longitudinal rows of cuticular papillae on inner surface. Genital double somite globose in its proximal half, with dorsal suture. Caudal rami each with three subequal setae.

Etymology

The new species is named with reference to Guerrero, the Mexican state from which this species was collected.

Remarks

Cymbasoma tumorifrons was named by Isaac (1975) from specimens collected at Emborios Bay, Aegean Sea, in the Mediterranean. This original description was brief and many morphological details were omitted. Suárez-Morales (1999, 2002) prepared a redescription of males and females of C. tumorifrons based on both the type material and the analysis of female specimens from Toulon Bay, southern coast of France. The record of C. tumorifrons from Mexico by Suárez-Morales and Alvarez-Silva (2001) was based on specimens collected from the Pacific coast of Mexico; the type material from Emborios Bay was consulted to confirm this record. Based on this re-examination and on an expanded set of characters, it is recognized here that, so far as we know now, C. tumorifrons is a Mediterranean species ( Isaac 1975) and the specimens from the Pacific coast of Mexico represent a new taxon.

Females of this new species can be distinguished from C. tumorifrons by several characters, including the relatively shorter antennules with respect to total body length (14.5% versus 16%), narrower cephalothorax in C. tumorifrons (4.1 times longer than it is wide versus 2.7 in the new species) and the cuticular ornamentation pattern on the cephalic area including the dorsal and ventral surfaces is different in both species (in C. guerrerense sp. nov. it includes one dorsal and one ventral fringe of transverse corrugation that are absent in C. tumorifrons ). Also, the ventral surface between the bases of the antennules and the oral papilla is protuberant in the new species and flat in C. tumorifrons . The insertion of the ovigerous spine is on the middle of the anterior half in C. guerrerense and on the posterior part of the anterior half of the somite in C. tumorifrons (see Suárez-Morales 2002). The fifth legs are widely divergent in C. guerrerense and not divergent in C. tumorifrons ; the rows of papilla-like elements on the fifth leg in the new species are absent in C. tumorifrons . In C. tumorifrons the antennular setal element 1 is strongly developed ( Suárez-Morales 2002), whereas it is reduced in the new species ( Suárez-Morales and Alvarez-Silva 2001); elements 4v 1–3 and 4d 1,2 are weakly developed in C. tumorifrons and are more strongly, or normally developed in the new species. Furthermore, in the new species antennular segments 3 and 4 are fused, whereas these segments are clearly separated in C. tumorifrons . This kind of fusion is a derived state common in species of Cymbasoma (Suárez- Morales et al. 2006).