Oxycephalus tenuirostris Claus, 1871: 155.
Leptocotis tenuirostris. — Siegel-Causey, 1982: 348‒349; Vinogradov et al., 1996: 522, fig. 226; García Madrigal, 2007: 157 (list); Gasca, 2009: 89 (tab. 1); Gasca et al., 2012: 126 (tab. 1); Valencia et al., 2013: 52 (tab. 1); Zeidler, 2016: 80‒82 (passim), figs. 37‒38; Violante-Huerta et al., 2021: 81 (tab. 1).
Leptocotis ambobus Stebbing, 1888: 1594.
Leptocotis spinifera Streets, 1877: 137‒138.
Material examined. 6M, 9F in seven localities (Fig. 1).
TALUD III. St. 3B (22°36’36”N, 106°35’54”W), August 17, 1991, 1M, 4F, I-K from surface to 275 m (TD, 1585 m) (ICML-EMU-12946-A); St. 19B (25°18’24”N, 109°18’36”W), August 20, 1991, 1M, 2F, I-K from surface to 600 m (TD, 1890 m) (ICML-EMU-12946-B); St. 25A2 (25°50’54”N, 109°56’54”W), August 21, 1991, 1F, I-K from surface to 230 m (TD, ca. 1200 m) (ICML-EMU-12946-C). TALUD V. St. 5 (22°00’57”N, 106°40’00”W), December 13, 2000, 2M, 1F, MN from surface To ca. 1400 m (TD> 1600 m) (ECOSUR-10558). TALUD VI. St. 15 (23°14’42”N, 107°30’W), March 14, 2001, 1M, MN, surface to 1300 m (TD, 2390 m) (ICML-EMU-12947). TALUD VII. St. 15 B (23°25’06”N, 107°47’31”N), June 7, 2001, 1M, MN from surface to 1425 m (TD, 2320 m) (ICML-EMU-12948). TALUD XII. St. 15C (17°27’51”N, 102°10’43”W), March 31, 2008, 1F, MN from surface to 1530 m (TD, 1880 m) (ICML-EMU-12949).
Distribution. Cosmopolitan, between 46°N and 41°S in all oceans; Mediterranean and Red Seas. In the eastern Pacific from California to Chile (Vinogradov et al. 1996, García Madrigal 2007, this study).
Remarks. This species was recognized by the typical shape of the rostrum, which is different between males and females, the long and characteristic urosoma, and the shape and size of pereopods I to III and of their corresponding coxae. Adult females were about 20 % smaller than adult males.
According to Siegel-Causey (1982), Leptocotis tenuirostris was very rare in the Gulf of California and found in two localities only, both at the entrance of the Gulf. Our material was roughly found in the same area, although more frequently (6 localities) and also off SW Mexico (Fig. 1). Although recorded in California, it has not been reported in the Mexican portion of the California Current by Lavaniegos & Hereu (2009) and Lavaniegos (2014).