Lestrigonus macrophthalmus (Vosseler 1901)

Lestrigonus macrophthalmus (Vosseler)

Hyperia macrophthalma Vosseler, 1901:70–72, pl. 6: fig. 16–25.–Yang. 1960:19–28, figs. 4–5.–Dick, 1970:56.

[?] Hyperia hydrocephala Vosseler.–Dakin & Colefax, 1940:121, fig. 206a-c.

DERIVATION OF NAME.–Not given, presumably from the Greek [=long] + [=eye]. Although Vosseler was technically incorrect grammatically in giving the noun thus formed a feminine ending and thereby treating it as an adjective (the correct adjective would have been macrophthalmata), I will continue the practice of other authors in considering the name an adjective.

TYPE-LOCALITY.–Six stations of the Plankton-Expedition in the tropical Atlantic.

DIAGNOSIS.–Length of ♀ 2–3.5 mm. of ♂ 3–4 mm. Head more globular than in other species, more than half as long as high, about as long as pereonites 1–4 combined. Pereonites 1–4 fused in ♀, 1–2 fused in ♂. Gland cone bluntly rounded below, in ♀ reaching or extending slightly beyond ventral border of buccal mass, in ♂ not reaching this border. Md incisor and lacinia with 7 teeth in immature ♀ dissected. Mx1 outer lobe with somewhat tapering apex extending well beyond distomedial spine. Mxp outer lobes slender, with 2 terminal setae and 2–3 setae on medial margin; inner lobe with 2 terminal spines. S2 of P1 with strong convexity on anterior margin; s4 with 2 posterodistal spines; s6 with 1 (♀) or 2 (♂) spines on anterior margin. P2 with carpal process about half as long as s6; s6 with 1 (♀) or 2 (♂) spines on anterior margin. S7 of P5 about ⅓–¼ length of s6, ¼ shorter than s7 of P6–7, armed with a few anteroproximal spinules; s6 of P6–7 with spine on distal margin overlapping base of s7 medially. Telson triangular, in ♀ about half, in ♂ less than half as long as protopod of Up3.

VARIATION.–As in other species of Lestrigonus the number of fused pereonites is greater in immature specimens, but never exceeds 5.

RELATIONSHIPS.–This species agrees with L. latissimus in having pereonites 1–4 fused in the female, but is distinguished by its smaller size and more globular head. In lateral view the gland cone overlaps the epistome less in macrophthalmus than in latissimus. Up protopod is more slender and longer in relation to the telson than in L. latissimus. S6 of P1–2 bears a single spine, whereas in L. latissimus s6 usually has 2 spines, but has 1 in immature specimens and in some adults. S7 of P5 is relatively shorter in latissimus than in macrophthalmus.

H. hydrocephala has been considered identical with H. macrophthalma, but I consider it to be an immature L. latissimus (see discussion under the latter species). Dakin and Colefax’s (1940) H. hydrocephala has the globular head of L. macrophthalmus and may be a young specimen in which pereonites 1–5 are fused.

DISTRIBUTION.–Tropical parts of the Atlantic, Pacific, and Indian Oceans. Not found in the CalCOFI area.