PRONOIDAE Claus, 1879

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 : 18-19

Family PRONOIDAE Claus, 1879

Diagnosis. Body length 10–14 mm, robust, slightly compressed laterally. Head bullet-shaped, slightly more pointed in males, as long as first four pereonites. Eyes large, occupying most of head surface. Coxae separate from pereonites. Antennae 1 of both sexes inserted in groove on ventral surface of head. Antennae 1 of females with 3- articulate peduncle; first flagellar article (callynophore) slightly enlarged, with row of aesthetascs on ventral margin, remainder of flagellum consists of two slender articles, inserted terminally. Antennae 1 of males similar to female except callynophore is larger, with aesthetascs arranged in two-field brush medially, and in separate group antero-ventrally. Antennae 2 of males 6-articulate, with some articles folded back on each other; only extending anteriorly under head. Antennae 2 of females 1-articulate. Mandibles with palp in both sexes. Maxillae 1 consisting of relatively well developed, curled, bifid lobes. Maxillae 2 also curled and relatively well developed, with rounded knobs terminally, and one-articulate palp medially, on the dorsal surface. Gnathopoda and pereopoda simple. Gnathopod 1 with enlarged basis, almost as broad as long. Pereopod 5 the longest, with slightly enlarged basis. Pereopod 6 with greatly enlarged basis, distinctly longer than remaining articles combined, which are inserted terminally. Pereopod 7 reduced to relatively large, quadrate basis and one tiny article, attached to antero-distal corner. Uropoda with articulated endopoda and exopoda. Telson triangular, about two-thirds as long as peduncle of U3, not fused with double urosomite. Gills without folds on pereonites 2–6. Oostegites on pereonites 2–5.

Genera. Pronoe Guérin-Méneville, 1836 .

Remarks. The family Pronoidae is restricted to the monotypic genus Pronoe , because it has some unique characters not found in any other platysceloidean.

Characters that distinguish Pronoe from other Platysceloidea are as follows. The antennae and mandibular palp are held in a narrow groove on the ventral surface of the head. The callynophore of the first antennae of males is spatulate, similar in shape to that found in Vibilia . The second antennae of males are reduced in size with a large, fleshy, quadrate basal article, attached for the most part to the buccal mass, and five slender articles terminally, folded only once. Both sexes have a 3-articulate mandibular palp of similar proportions. The maxillae are relatively large, and distinctly curled inwardly. The first maxillae are relatively simple and bifid. The second maxillae have, what appear to be, an inner palp, analogous to the inner plate found in the Gammaridea. Pereopod 7 is also unusual in that it is reduced to a relatively large, quadrate basis and one tiny, pointed article attached to the antero-distal corner.

None of the above characters are shared by Eupronoe , Parapronoe or Paralycaea , genera which have previously been included in the Pronoidae ( Vinogradov et al. 1982) . Thus, they are removed from the family Pronoidae . Eupronoe and Parapronoe share a number of characters (see later), and they are here placed in the new family Eupronoidae fam. nov. Paralycaea however, differs from Eupronoe and Parapronoe , and is placed in a new family, Amphithyridae fam. nov., together with Amphithyrus and Amphithyropsis gen. nov.; genera with which it shares a number of characters (see later).