Themistella fusca ( Dana, 1853 )

Gasca, Rebeca & Hendrickx, Michel E., 2021, Pelagic amphipods (Crustacea: Amphipoda: Hyperiidea) in western Mexico. 3 Family Lestrigonidae, Zootaxa 4974 (1), pp. 169-187 : 180-181

Themistella fusca ( Dana, 1853)

Lestrigonus fuscus Dana, 1853: 983 , pl. 67, fig. 8a

Themistella steenstrupi Bovallius, 1887: 23 ; 1889: 313.

Themistella fusca — Bowman, 1973: 66, fig. 51; Siegel-Causey, 1992: 195; Vinogradov et al., 1996: 400, fig. 173; Zeidler, 2004: 33; Brusca & Hendrickx, 2005: 150 (list); García Madrigal, 2007: 151 (list); Valencia & Giraldo, 2012: 1492 (tab. 1); Lavaniegos & Hereu, 2009: 139, 142 (tab. 1), 146 (tab. 2), 151 (Appendix 1).

Material examined. 2F, in two localities ( Fig. 7 ). TALUD III. St. 19B (25°18’24”N, 109°18’36”W), August 20, 1991 , 1F, I-K, from surface to 600 m (TD, 1890 m) (ICML-EMU-12811). TALUD VII. St. 36 (25°42’37”N, 110°04’35”W), June 9, 2001 , 1F, MN, from surface to 1390 m (TD, 2400 m) (ICML-EMU-12812) .

Distribution. Atlantic, Pacific, and Indian oceans. In the eastern Pacific from off Baja California, Gulf of California, and south to off Guatemala and Nicaragua ( García Madrigal 2007).

Remarks. A commonly collected species in the central and southern Gulf of California, T. fusca has mostly been found in epipelagic layers ( Siegel-Causey 1982). Also found in the Mexican tropical Pacific ( Gasca et al. 2012).

Only two female specimens were found. Specimens measured about 2.5 mm in length. Five thoracic segments are fused; fourth segment partially free dorsally. Dactyli of pereopods VI and VII distinctively bent upwards. Telson small and rounded. There are only two other lestrigonids known to have five thoracic segments fused: L. bengalensis (male juveniles) and L. ducrayi Zeidler, 1992 which has a proportionally longer telson and a shorter pereopod 2 carpal process.

Figures

FIGURE 7. Localities where Lestrigonus schoemakeri, Phronimopsis spinifera, and Themistella fusca were captured during this survey. x 2: two samples at same localities in different cruises.