Tryphanidae Boeck 1871

Family TRYPHANIDAE Boeck, 1871

Diagnosis. Body length up to 6 mm, relatively robust. Head rounded, relatively large, as long as first three pereonites. Eyes large, occupying most of head surface. Coxae separate from pereonites. Antennae 1 of females with 2-articulate peduncle, and enlarged first flagellar article (callynophore), with about five aesthetascs grouped near postero-distal corner, followed by one slender, terminal article. Antennae 1 of males with 2-articulate peduncle, and almost spherical, first flagellar article (callynophore), with single brush of aesthetascs on posterior margin; second flagellar article is slender and about as long as previous articles combined; third flagellar article is very slender and small, and is inserted sub-terminally, together with row of three aesthetascs. Antennae 2 of females consists of two, broad, slightly curved articles. Antennae 2 of males with relatively short, enlarged basal article, followed by four slender articles of similar length, folded back on one another, the terminal article being more slender and slightly longer than any other; slender, folded articles held obliquely and dorsally in cavity of head. Mandibles with incisor with distal corner produced into pronounced, rounded lobe medially; palp 3-articulate in males, 2-articulate in females. Maxillae 1 reduced to small quadrate lobes. Maxillae 2 reduced to small rounded lobes. Gnathopoda simple. Gnathopod 1 with enlarged basis, almost as broad as long. Pereopods 3–6 with robust articles, dactylus closing against produced distal margin of propodus. Pereopod 5 the longest. Pereopod 7 reduced in size but with full complement of articles; basis as long as remaining articles combined. Uropoda all with articulated endopoda and exopoda. Telson triangular, about a long as peduncle of U3, not fused with double urosomite. Gills on pereonites 2–6, some with folds on pereonite 5 or 6, or both. Oostegites on pereonites 2–5.

Genera. Tryphana Boeck, 1871.

Remarks. This family has had a chequered history. It was proposed by Boeck (1871) for his new genus and species, Tryphana malmi. Bovallius (1887) expanded it to also include Brachyscelus (as Thamyris), Thamneus, Lycaea, Paralycaea, Pseudolycaea (= Lycaea) and Simorhynchotus (as Simorhynchus). Later (1890) he dispensed with the family altogether, placing Lycaea and Pseudolycaea in the family Lycaeidae, Brachyscelus and Thamneus (changed to Euthamneus) in a new family, Euthamneidae, and placed Paralycaea in the family Pronoidae and Simorhynchotus in the family Oxycephalidae; Tryphana, for some obscure reason, is considered to be like Lycaeopsis and is placed with it in the family, Phorcidae (= Lycaeopsidae). However, subsequent authors have included Tryphana in the family Lycaeidae (e.g. Chevreux & Fage 1925, Stephensen 1925, Bowman & Gruner 1973). Vinogradov et al. (1982) recognised the unique characters of Tryphana and reinstituted the family Tryphanidae, but mistakenly attribute it to Bovallius 1887. Not all subsequent authors have accepted this change (e.g. Shih & Chen 1995).

Tryphanidae, represented by Tryphana, has a number of unique characters that readily distinguish it from all other families of Platysceloidea as follows. The morphology of the first antennae of males is unlike any other hyperiidean. The second antennae of males have a whip-like terminal article, which is longer than any preceding one, and the slender, folded articles are held obliquely and dorsally in a cavity in the head; a unique character only discovered recently while examining fresh specimens. The second antennae of females (absent in Lycaeidae) are also unusual, and consist of two, broad, slightly curved articles, pressed closely to the side of the head. The mandibles have an incisor with the distal corner produced into a rounded lobe, which is unusually large. Females also have a 2-articulate mandibular palp; Pronoe is the only other genus in which females have a mandibular palp (3-articulate). The inner lobes of the maxilliped are divided for about half their length. The morphology of the gnathopoda is unusual but approach those of Pronoe. Pereopods 3–6 are almost prehensile, whereas they are simple in all other Platysceloidea.