Merhippolyte americana Holthuis, 1961

Pachelle, Paulo P. G., Anker, Arthur, Mendes, Cecili B. & Bezerra, Luis E. A., 2016, Decapod crustaceans from the state of Ceará, northeastern Brazil: an updated checklist of marine and estuarine species, with 23 new records, Zootaxa 4131 (1), pp. 1-63 : 12-16

Merhippolyte americana Holthuis, 1961

( Figures 7 , 8 )

Merhippolyte americana Holthuis 1961: 1 , fig. 1.

Material examined. Brazil, Ceará: 1 male, 1 ov. female, MZUSP 31505, 222 km (120 nautical miles) off Fortaleza, Banco Canopus, 60–70 m, coll. J. Coltro, 20.xi.2005.

Distribution. Western Atlantic: USA (North Carolina), Brazil (Ceará, São Paulo, Rio Grande do Sul), Argentina (Buenos Aires) ( Christoffersen 1998; present study).

Remarks. The present material from Ceará agrees well with the description of Merhippolyte americana provided by Holthuis (1961), except for a few morphological details. For instance, in the Ceará specimens, the rostrum bears three dorsal teeth (vs. four in Holthuis’ material); the second pereiopod carpus has 12 joints (vs. 13- 14 in Holthuis’ material), whilst the ischium is articulated (vs. not articulated in Holthuis’ description); the third pereiopod merus bears only one spiniform seta (vs. two in Holthuis’s material); the appendix masculina on the second male pleopod is shorter than appendix interna (vs. slightly longer than appendix interna in Holthuis’ description); and finally, the distal margin of the telson is shorter, about the same length as the lateral pair of distal spiniform setae (vs. longer, at least twice the length of these spiniform setae in Holthuis’ material) (cf. Figs. 7 B, E, J, 8A, E, F and Holthuis 1961: fig. 1a, c, m, n, p). In addition, the third maxilliped bears one small spiniform seta on the distolateral margin of the antepenultimate article ( Fig. 7 G), which, however, may have been overlooked by Holthuis (1961). For the time being, these differences are considered to be part of intraspecific variation of the species; however a further, more detailed comparison (including COI gene) between the populations from Brazil and the eastern USA is highly desirable. To our knowledge, the present material represents the first record of M. americana from northeastern Brazil.

Figures

FIGURE 7. Merhippolyte americana Holthuis, 1961: male from Banco Canopus, off Fortaleza, Ceará, Brazil (MZUSP 31505); A, frontal region, dorsal view; B, same, lateral view; C, abdomen, fourth to sixth somites, lateral view; D, telson, dorsal view; E, same, distal region, dorsal view; F, right third maxilliped, tip of ultimate article, ventral view; G, same, detail of small spiniform seta on antepenultimate article, lateral view; H, right first pereiopod, lateral view; I, same, fingers, ventromesial view; J, right second pereiopod, lateral view; K, right uropod, dorsal view.

FIGURE 8. Merhippolyte americana Holthuis, 1961: male from off Fortaleza, Ceará, Brazil (MZUSP 31505); A, right third pereiopod, lateral view; B, right fourth pereiopod, lateral view; C, right fifth pereiopod, lateral view; D, right first pleopod, ventral view; E, right second pleopod, ventral view; F, same, appendices interna and masculina, dorsal view; G, right third pleopod, ventral view.