Lycaea vincentii Stebbing 1888

Lycaea vincentii Stebbing, 1888

(Figs 20–21)

Lycaea vincentii Stebbing, 1888: 1563–1566, pl. 199.— Stewart 1913: 262–265.— Barnard 1930: 429–430, fig. 57.—Harbison 1976: 160–161, fig. 13.— Harbison & Madin 1976: 167–169, figs 1C, 3D, 5B.— Madin & Harbison 1977: 456.— Schulenberger 1977: 379 (tab.).— Zeidler 1978: 27, fig. 27.— Laval 1980: 20 (tab.).— Stuck et al. 1980: 365–366.— Zeidler 1984: passim.— Young & Anderson 1987: 717 (tab.), 721.— Young 1989: 715 (tab.).— Diebel 1992: passim.— Zeidler 1992: 119–120.— Shih & Chen 1995: 171 (key), 173–174, fig. 112.— Zeidler 1998: 104, 107.— Vinogradov 1999: 1195 (key).— Lowry 2000: 327 (list).— Lima & Valentin 2001: 473 (list), 474 (tab.).— Escobar-Briones et al. 2002: 367 (list).— Gasca 2003a: 308 (tab.).— Gates et al. 2003: 322.— Gasca 2007: 119 (tab.).— Gasca 2009a: 89 (tab.).— Gasca 2009b: 66 (tab.).— Gasca 2009c: 218 (tab.).— LeCroy et al. 2009: 969 (tab.).—Gasca et al. 2012: passim.— Gasca & Franco-Gordo 2014: 75 (list).

Lycaea Vincentii. — Pirlot 1929: 137.

Lycaea Vincenti. — Pirlot 1939a: 45.

Lycaea vincenti. — Vinogradov 1990: 76, 94 (tab.).— Vinogradov 1991: 261 (tab.).— Lin & Chen 1994: 118 (list).— Lin et al. 1996: 230 (tab.).— Vinogradov & Semenova 1996: 615.— Gasca & Franco-Gordo 2008: 569 (tab.), 571–572.

Lycaea bajensis.— Barnard 1931: 129–130.— Dakin & Colefax 1940: 124, fig. 214. [mis-identification].

Amphipronoe longicornuta Giles, 1888: 220–224, pl. 5. NEW SYNONYMY.

Lycaea longicornuta. — Barnard 1930: 429.— Harbison et al. 1976: 169.

Type material. The unique holotype male (about 5 mm) of Lycaea vincentii is in the NHM, London (89.5.15.309), on two microscope slides. The type locality is the N.E. Atlantic, off St Vincent, Cape Verde Islands [16°49’N 25°14’W], Challenger, surface, 26 April 1876.

Type material of synonyms. Type material of Amphipronoe longicornuta, consisting of one female and one male (whole but dry), is in the NHM, London (1909.4.3.6), on one microscope slide. The type locality is the Bay of Bengal. Barnard (1930) suggested that this species may be synonymous with L. bajensis. Harbison et al. (1976), on the other hand, consider it to be near L. vincentii. An examination of the type material has confirmed the latter synonymy.

Material examined. Type material of Lycaea vincentii and Amphipronoe longicornuta as detailed above and the following. In NHMD: S.E. Atlantic, off Angola, Galathea stn. 98 [08°52’S 11°09’E], 2820 m, 3 females, 6 males, “with salps”. Tropical Pacific, Dana stn. 3722 v, S.E. of Taiwan [25°11’N 122°35’E], 50 mw, 1 female; Galathea stn. 745, Gulf of Panama [07°15’N 79°25’W], 935 m, 2 females, 2 males. In SAMA: Coral Sea, Great Barrier Reef, north-east of Townsville, 44 females, 21 males (23 lots), C12622–44. Tasman Sea, off eastern Australia [20°– 40°S], 13 females, 8 males (16 lots), C5283–99. In USNM: N.W. Atlantic, from the Sargasso Sea in the south, north to Delaware Bay, 8 females, 18 males (9 lots), 12880, 108144, 181802, 1178021, 1241178, 1246975, 1246980, 1242792, 1242794. S.W. Atlantic, off Brazil [02°07’N 44°02’W], 1 male, 1246987. N. Pacific, Hawaii [23°19’N 166°54’W], 1 male, 1242805. Japan, Colnett Strait, S.W. of Yaku Shima, 5 males, 1246963.

Diagnosis. Body length up to 6.0 mm. Head of females relatively large, deeper than long, as long as first 4 pereonites combined. Head of males more rounded, slightly elongated, marginally deeper than long, almost as long as first 5 pereonites combined. Buccal mass protruded well below head. Callynophore of A1 of males with distinct antero-distal corner, set back slightly from distal margin; postero-distal corner small, acutely rounded, separated from following article by distinct notch. G1 and G2 sub-chelate, morphologically similar, G2 slightly longer than G1; basis of G1 slightly broader and shorter than G2; carpus rectangular with sharp postero-distal tooth, reaching just past base of dactylus; propodus with postero-distal corner produced posteriorly to dactylus; carpus and propodus with small serrations on distal margins, those on posterior margin of carpus of G1 prominently scalloped; dactylus slender, length about 0.6 x propodus, or marginally longer in females. P3–6 with relatively slender dactylus of moderate length, those of P4 about 0.3–0.4 x propodus. P3 and P4 morphologically similar, P4 slightly longer than P3; merus slightly inflated anteriorly, sub-equal in length to propodus, about 0.6 x basis; carpus length about 0.6–0.7 x propodus. P5 slightly longer than P4 or P6; basis rectangular/oval, length 1.8–2.0 x maximum width; merus sub-equal in length to propodus, about 0.6–0.7 x basis; carpus length about 0.7 x propodus. P6 basis more oval-shaped than P5 but almost equal in length, slightly broader in males with length 1.5 x maximum width (2.0 x in females); merus sub-equal in length to propodus, about 0.4 x basis; carpus length about 0.5 x propodus; anterior margin of carpus and propodus, and antero-distal corner of merus, slightly serrated. P7 basis with bulging posterior margin, more prominent in males, length about 1.4 x maximum width in males (about 1.7 x in females), length about 0.7 x basis of P6 for both sexes; length of remaining articles about 0.3 x basis; propodus with antero-distal corner produced into small, rounded lobe; dactylus sharp, hook-like. U1 and U2; endopod not fused with peduncle. U1 peduncle length 3.5 x exopod, or slightly more; rami relatively slender, equal in length. Telson as long as width at base in males, slightly longer in females.

Remarks. In the past, Lycaea vincentii has been considered a synonym of L. pulex, but it is distinguished by the medium length dactylus of P3–6, and the relatively long peduncle of U1 (see Harbison 1976). Males are further distinguished by the distinctive antero-distal bulge of the callynophore of A1 which is absent in all other congeners except for L. bovallii. It is also a relatively smaller species reaching maturity at 5–6 mm, compared to 9 mm for L. pulex. Another distinctive character is that the posterior margin of the carpus of G1 is distinctly scalloped rather than serrated, a character not found in any other species except perhaps L. bovallii, but in that species the margin is more serrated than scalloped and is much less prominent. Clearly Lycaea vincentii is most closely related to L. bovallii but is distinguished by the characters as discussed under that species.

Regarding Amphipronoe longicornuta Giles, 1888 the date given for this reference is often 1887 which would predate L. vincentii Stebbing, 1888 and create a potential nomenclatural problem. However, this species has not been reported since its original description and the volume containing Giles’s description was not published until 1888, the volume being “for the year 1887”.

The only recorded associates are with the salps Salpa cylindrica and Thalia democratica (Forsskål, 1775) (Harbison 1976) and also Pegea confoederata (Madin & Harbison 1977).

Diebel (1992) provides some interesting information on the integumentary sensilla.

Distribution. Difficult to determine because of the past confusion with other species. However, it is probably widespread in the tropical and temperate regions of the Pacific and Atlantic. It is relatively common off the eastern coast of Australia. Other reliable records are from the northern Atlantic, the N.E. Pacific and the South China Sea.