Lycaea nasuta Claus 1879

Lycaea nasuta Claus, 1879

(Figs 8–9)

Lycaea nasuta Claus, 1879: 185 (39).— Bovallius 1887: 32.— Claus 1887: 62, pl. 18, figs 1–7.— Chevreux 1927: 140.— Barnard 1930: 430–431, fig. 59.— Barnard 1932: 291.— Hurley 1955: 180 (key).— Kane 1962: 310.— Siegfried 1963: 6 (list), 10.— Dick 1970: 67.— Harbison & Madin 1976: 165–167, figs 1–2.— Madin & Harbison 1977: 453 (tab.), 456.— Laval 1980: 20 (tab.).— Vinogradov et al. 1982 /1996: 382/472 (key), 385/475–477, fig. 207 (G2 is not of this species).— Vinogradov 1990: 74–75, 94 (tab.).— Vinogradov 1991: 261 (tab.).— Vinogradov 1993: 45 (tab.).— Lin et al. 1996: 230 (tab.).— Barkhatov et al. 1999: 808 (tab.).— Vinogradov 1999: 1146 (tab.), 1194 (incl. key), fig. 4.138.— Escobar-Briones et al. 2002: 367 (list).— Brusca & Hendrickx 2005: 151 (list).— Browne et al. 2007: 819 (tab.), 825, fig. 4 (phylogenetic tree).—Garcia- Madrigal 2007: 155, 192 (list).— Gasca 2009a: 89 (tab.).— Lavaniegos & Hereu 2009: passim.— Zeidler & De Broyer 2009: 71.— Hurt et al. 2013: 31 (tab.), figs 1, 2 (phylogenetic).— Espinosa-Leal & Lavaniegos 2016: 150 (tab.).— Hereu et al. 2020: 9 (tab.), passim.— Lavaniegos 2020: passim.

Type material. Type material of Lycaea nasuta could not be found in any major European institution and is considered lost. The type locality is the W. Indian Ocean, off Zanzibar. Claus’s (1887) illustration of a male, although limited to the habitus, gnathopods and uropods, readily characterise this distinctive species.

Material examined. In NHMD: tropical Atlantic, Dana stn. 3998 xi (228229), 1 male; Dana stn. 4000 iii (228230), 2 females. S. Pacific, Dana stn. 3561 iv (228145), 1 female. In USNM: N.W. Atlantic, from the Bahamas in the south, north to Georges Bank, off Massachusetts, 9 females, 5 males (6 lots), 10878, 1241181, 1241239, 12421289, 1246893., 1246974. S.W. Atlantic, off Brazil [01°06’S 35°10’W], 1 female, 1247115. N. Pacific, off Hawaii [19.42°N 156.07°W], 1 female, 1196356.

Diagnosis. Body length of mature females up to 8.0 mm and males up to 9.0 mm. Head of females relatively rounded, slightly deeper than long, as long as first 4 pereonites combined; the eyes more massive than in other species, wider than anterior pereonites in dorsal view. Head of males (when mature) with distinctive rounded knob anteriorly, relatively smaller than for females, slightly deeper than long, almost as long as first 4 pereonites combined. Buccal mass protruded only slightly below head. Callynophore of A1 of males without antero-distal corner; postero-distal corner small, rounded, partly over-lapping following article. G1 and G2 sub-chelate, G2 slightly longer than G1. G1 basis slightly shorter than that of G2, inflated anteriorly with evenly rounded anterior margin; carpus rectangular with small, sharp, postero-distal tooth, reaching just past base of dactylus; propodus with small, rounded, postero-distal corner produced posteriorly to dactylus; dactylus relatively short, curved, length about 0.3 x propodus. G2 basis relatively slender; carpus narrow, postero-distal tooth only reaching to about 0.6 x posterior margin of propodus; propodus and dactylus like that of G1. P3–6 with relatively short, stubby dactylus, those of P3 and P4 slightly less than 0.2 x propodus. P3 and P4 morphologically similar, P4 slightly longer than P3; merus slightly inflated anteriorly, sub-equal in length to carpus, about 0.8 x propodus and almost 0.5 x basis. P5 relatively longer than for other species, about 1.5 x P4 and P6 (slightly less in males); basis rectangular, length slightly more than 2 x maximum width; merus length about 0.8 x propodus, almost 0.7 x basis; carpus length slightly less than 0.6 x propodus. P6 basis rectangular, length about 2 x maximum width, slightly shorter than basis of P5; merus slightly inflated anteriorly; merus, carpus and propodus similar in relative lengths to P5; anterior margin of carpus and propodus, and antero-distal corner of merus, slightly serrated. P7 basis with bulging posterior margin, length about 1.5 x maximum width, about 0.7–0.8 x basis of P6; length of remaining articles about 0.5 x basis, or slightly more; propodus with antero-distal corner produced into rounded lobe; dactylus sharp, hook-like. U1 peduncle relatively wider than for other species, length about 3.0 x exopod; endopod rarely fused with peduncle; rami relatively broad, equal in length. U2 endopod fused with peduncle. Telson slightly longer than width at base, with evenly rounded apex.

Remarks. A combination of three characters distinguishes Lycaea nasuta from its congeners: i) the relatively short dactylus of P3 and P4; ii) the narrow carpus of G2, which is shorter than the posterior margin of the propodus; and iii) the fusion of the inner ramus of U2 with the peduncle. The morphology of G2 is similar to L. lilia and L. osbornae sp. nov., but in the former the postero-distal corner of the carpus is rounded and in the latter the carpus is more rectangular and the dactylus is more slender and longer; also the morphology of G1 and G2 is similar. Lycaea nasuta also bears some similarity to L. intermedia, as discussed under that species.

Lycaea nasuta has, to date, only been recorded with the salp Cyclosalpa affinis (Chamisso, 1819) (Madin & Harbison 1977).

Distribution. Known only from a few records; from the Indian and Atlantic Oceans around South Africa, from the north and S.E. mid-Atlantic, and from the Pacific Ocean, in the south, near New Zealand to about 42°S, and in the north off the eastern coast of America, from California to Mexico and off Peru and Chile. Most catch records are from near the surface.