Tullbergella Bovallius, 1887

Zeidler, Wolfgang, 2016, A review of the families and genera of the superfamily PLATYSCELOIDEA Bowman & Gruner, 1973 (Crustacea: Amphipoda: Hyperiidea), together with keys to the families, genera and species, Zootaxa 4192 (1), pp. 1-136 : 89-90

Genus Tullbergella Bovallius, 1887

( Figs 43–44 )

Tullbergella Bovallius, 1887: 38 .— Bovallius 1890: 46 (key), 68–69.— Spandl 1927: 179 (key).— Yoo 1971: 63 (key).— Bowman & Gruner 1973: 49 (key), 53–54.— Zeidler 1978: 30 (key), 33.— Vinogradov et al. 1982: 404 (key), 425.— Nair 1995: 6 (key), 13.— Shih & Chen 1995: 190 (key), 223.

Type species. Tullbergella cuspidata Bovallius, 1887 by monotypy. Type material could not be found at the NRS, ZMUC or in Upsala and is considered lost. However, Tullbergella is a very distinctive genus whose status has been confirmed by the later work of Bovallius (1890). No precise type locality is given by Bovallius (1887), just the “ Indian Ocean ”.

Diagnosis. Body shape robust or globular. Head round. Rostrum relatively short, pointed. Eyes occupying most of head surface; grouped in one field on each side of head. Antennae 1 of males with 2-articulate peduncle; flagellum with large, crescent-shaped callynophore, with relatively large antero-distal lobe, with aesthetascs arranged in two-field brush medially, with three smaller articles inserted below antero-dorsal corner. Antennae 1 of females with two articulate peduncle; callynophore with proximal bulge and row of aesthestascs medially and distally, with two smaller articles inserted terminally. Antennae 2 absent in females. Antennae 2 of males 5- articulate; strongly zig-zagged, with most articles folded back on each other; extending anteriorly under head and posteriorly between the gnathopoda and pereopoda to pereonite 5; basal article distinctly inflated, about half or less the length of following article; terminal article, short, not folded, pointing posteriorly. Mandibular palp 3-articulate in males. Mandibular incisor relatively broad, with several teeth, with small distal lobe medially; in male orientated more or less parallel to palp. Maxillae 1 consisting of rounded plates. Maxillae 2 absent. Maxilliped with inner lobes completely fused; medial margin of outer lobes with membranous fringe. Coxae all separate from pereonites. Gnathopods 1 & 2 sub-chelate; carpal process knife-shaped, armed with prominent teeth and setae. Pereopods 3 & 4 sub-equal in length to pereopods 5 & 6. Pereopod 5; basis 2– 3 x as wide as merus; articles 3–7 relatively slender, inserted terminally to basis. Pereopod 6; basis about twice as wide as merus, with prominent upturned posterodistal corner; articles 3–7 inserted terminally to basis. Pereopod 7 reduced in size with large basis; with only 1–3 terminal articles. Uropods 1 & 2 with articulated exopoda and endopoda. Uropod 3; endopod fused with peduncle. Rami of all uropoda lanceolate, usually with serrated margins. Telson fused with double urosomite. Oostegites on pereonites 2–5. Gills on pereonites 2–6; all with folds.

Species. Tullbergella cuspidata Bovallius, 1887 .

Sexual dimorphism. The sexes are remarkably similar in general morphology and, except for the antennae and mandibles, no additional sexual dimorphism could be determined amongst the limited material examined.

Remarks. This genus is readily distinguished by the morphology of the rostrum, gnathopoda, pereopoda and urosome. The relatively short, sharp rostrum, robust body, and thick cuticle are also unlike other members of Oxycephalidae .

Tullbergella has a number of unusual characters that differ from most other members of the family. The first antennae of females are like those of Tetrathyrus (and Streetsia ) in that the callynophore has a proximal bulge. Other genera of Platyscelidae are also similar in this regard but the bulge on the callynophore is located distally. The first antennae of males are more like those of Simorhynchotus (Lycaeidae) than other genera of Oxycephalidae . The second antennae of males are also like those of Lycaeidae in general morphology, and in that they extend under the body to pereonite 5. In all other genera of Oxycephalidae the second antennae of males are projected under the head for most of their length, and extend posteriorly only to pereonite 1, or rarely to pereonite 2. The mandibles are also more like those of Lycaeidae , and the maxillae resemble the families Brachyscelidae , Lycaeidae and most genera of Oxycephalidae .

Amongst the family Oxycephalidae , Tullbergella is most similar to Streetsia in the morphology of the first antennae of females, and the maxilliped, and in that the head is without a neck (except for S. mindanaonis ). In having the coxae not fused with the pereonites it resembles Leptocotis , Glossocephalus (fused with pereonite 7) and Streetsia .

Tullbergella is a relatively rare genus and consequently very little is known about its biology. Barnard (1931) recorded it on medusae, “? Cotylorhiza sp.”, and some SAMA specimens, also from the outer Barrier Reef, were found “under medusae”. In this regard it is unlike most other Oxycephalidae , which are preferentially associated with ctenophores.

Tullbergella cuspidata seems to prefer surface waters in tropical regions, and has been recorded from the South China Sea, the Java Sea, the Great Barrier Reef, the Indian Ocean south-west of India, and from the Atlantic Ocean near Barbados .

Figures

FIGURE 43. Tullbergella cuspidata Bovallius, 1887, male (8.0 mm), Coral Sea, SAMA C 3698. A, habitus. Scale bars = 1.0 mm (A), 0.5 mm (remainder).

FIGURE 44. Tullbergella cuspidata Bovallius, 1887, female (11.5 mm) and male (7.0 mm), Coral Sea, SAMA C 564. Scale bars = 0.05 mm (Mx 1, Md-r), 0.2 mm (remainder).