Vibilia robusta Bovallius 1887

Vibilia robusta Bovallius (Figs 7­9)

Vibilia robusta Bovallius, 1887a: 7­8. — Bovallius 1887c: 54–57, pl. 7, figs 12–34. Vosseler 1901: 123. Walker 1909: 50, 53. Behning 1913a: 529. Behning 1913b: 215. Stephensen 1918: 37–38, fig. 9. Behning 1927: 116–117, 121 (Table), fig. 2. Chevreux 1935: 175. Hurley 1960a: 110. Semenova 1973: 170: Semenova 1976: 136­138. Brusca 1981: 18 (key), 39, fig. 4i. Vinogradov et al. 1982: 214–216, fig. 106. De Broyer & Jazdzewski 1993: 112. Zeidler 1998: 37, figs 25–27. Vinogradov 1999: 1180, fig. 4.88.

Vibilia hirsuta Behning & Woltereck, 1912: 6–8, figs 4–6. — Behning 1913b: 220. Behning 1925: 489–491, figs 42–51.

Type material

Type material of V. robusta could not be found at the SMNH, ZMUC or in Uppsala and is considered lost. However, in the SMNH are several lots from the Atlantic that may have been part of Bovallius’s original material. Fortunately the descriptions and figures of Bovallius (1887c) readily characterise this species. No precise type locality is given by Bovallius (1887a, c). He merely lists the distribution as “Atlantic, Indian Ocean” (1887a), and “North Atlantic, tropical Atlantic” (1887c).

Type material of synonyms

Type material of V. hirsuta could not be found in the ZMB, or ZMH and is considered lost. However, this species is clearly the same as V. robusta, judging by the figures and description of Behning and Woltereck (1912).

Material examined (> 100 specimens)

Tasman Sea: 9 lots (SAMA), 14 specimens. Great Australian Bight: 4 lots (SAMA), 13 specimens. North Atlantic: 1 lot (ZMB), 2 lots (ZMH), 5 lots (ZMUC), numerous specimens. South Atlantic: 2 lots (ZMUC), 7 specimens. North Pacific: 1 lot (CAS), 2 lots (LACM), 1 lot (USNM), 11 specimens. South Pacific: 2 lots (BMNH), 20 specimens. Philippines: 1 lot (USNM), 4 specimens.

Diagnosis

Body length up to 20 mm. Antennae 1; as long as head and first pereonite; flagellum oval, evenly rounded terminally, slightly truncate ventrally in mature specimens. Gnathopod 2; basis inflated in mature specimens, width about 0.7x length; carpal process about 0.7x length of propodus. Pereopods 3 & 4; dactylus length about 0.3x propodus. Pereopods 5 & 6; dactylus length about 0.2x propodus. Pereopod 7; basis rectangular, a little longer than wide, slightly longer than ischium to carpus combined, without prominent posterodistal lobe in juvenile specimens. Lateral corners of last urosomite not produced. Uropod 2 reaching to tip of U3, or slightly beyond. Uropod 3; peduncle distinctly longer than rami, subequal in juvenile specimens; sexual dimorphism of endopod not evident. Telson triangular, with rounded point, length about half peduncle of U3.

Remarks

This is one of the largest species of Vibilia. The relatively long uropod 2 and the relatively wide basis of the gnathopods, especially gnathopod 2, are distinctive features not found in any other species of Vibilia. Juvenile specimens differ slightly from mature ones and may present taxonomic difficulties. Thus, an immature female is illustrated (Figs 7­9) for comparison. In particular mature specimens have slightly larger eyes; the main flagellar article of antennae 1 is slightly truncate ventrally; the basis of the gnathopods is considerably wider; the merus of gnathopod 2 has more spines; the basis of pereopod 7 has a distinct posterodistal lobe overlapping the ischium; the ridges on coxae 5­7 and the pleon are more prominent, and the peduncle of uropod 3 is distinctly longer than the rami. Specimens less than about 5 mm in length also have a much shorter telson, and pereopod 7 is often considerably reduced in size. However, despite these differences, juvenile specimens of V. robusta can be readily distinguished by the relatively long uropod 2.

This species is often recorded in association with salps but the host species is rarely recorded. Behning (1927) records it with Salpa tilesii (= Thetys vagina). In Californian waters it is found with Thetys vagina (specimens in LACM).

Distribution

This species is widely distributed in all the world’s oceans, ranging from tropical to temperate regions.