Julmarichardiidae, Moralés-Núñez & Heard, 2021

Moralés-Núñez, Andres G. & Heard, Richard W., 2021, Julmarichardiidae, a new apseudoidean family (Crustacea: Tanaidacea: Apseudomorpha) with the description of a new species of Julmarichardia Guţu 1995 from the Northwest Australian Shelf, Zootaxa 5081 (1), pp. 77-115 : 78-80

Family Julmarichardiidae fam. nov.

Type genus. Julmarichardia Guţu, 1989

Diagnosis. Antenna with squama. Rostrum well-developed spatulate or triangular, margins with or without spines or spinules, and with or without plumose setae. Cheliped and pereopod-1 with exopod. Pereopod-1 with strongly developed coxal process dorsal margin bearing plumose setae and with or without spines. Mucus glands and reservoir packets dispersed throughout body and appendages with ducts opening on dactylus of pereopod-1. Pleon unfused, with five pairs of well-developed biramous pleopods.

Etymology. From the double-patronym, type-genus, Julmarichardia .

Remarks. Julmarichardiidae fam. nov. and the Numbakullidae Guţu & Heard, 2002 , are both small highly derived families, both of which are presently known from the Southwest Pacific and Indian Ocean. Based on the morphology of their appendages, primarily the pereopods, and other meristic features, both appears to have evolved from the same progenitors that gave rise to the family Metapseudidae Lang, 1970 . These two small families, unlike members of the larger, more diverse, and widely distributed Metapseudidae , are characterized by the presence of mucus glands and reservoir mucus packets throughout their bodies and appendages.

Like the julmarichardiids, numbakullids are represented by a single genus and a few (three) species ( Stępień 2013); they are unique by having dense rows of long plumose setae on the posterior margins of the merus and carpus on pereopod-1 ( Guţu & Heard 2002: figs 1B, 3C). These setal modifications, which immediately distinguished numbakullids from the julmarichardiids and the metapseudids, appear to be an adaptation to facilitate suspension and/or filter feeding (Ibid) and maybe analogous to that of the kalliapseudids.

The distinctive presence of mucus glands, a prominent anteriorly-directed coxal process on pereopod-1, and a strongly developed broad rostrum distinguish Julmarichardiidae from the Metapseudidae , where it (the genus) was originally placed by Guţu (1989a). Except for these distinctive differences, the general morphology of Julmarichardiidae appears to be most similar to that of the metapseudid Subfamily Chondropodinae Guţu, 2008 . Both groups share several apparent plesiomorphic characters, including the presence of an antennal squama, exopods on the cheliped and pereopod-1, and unfused pleonites bearing five pairs of well-developed pleopods. As mentioned earlier, these similarities indicate that the two groups may have been derived from the same ancestral stock.

Besides the Julmarichardiidae and Numbakullidae , only two other apseudomorphan families, the Kalliapseudidae Lang, 1956 and Parapseudidae Guţu, 1981 (see Drumm 2005; Kakui & Hiruta 2014, 2017; Morales-Núñez et al. 2017) are known to have distinct mucus glands. The mucus produced by these glands is used, at least in part, in the construction of domiciles ( Drumm 2005; Morales-Núñez et al. 2017; Heard et al. 2018). One of us (RWH) when initially sorting tanaidaceans samples from the NW Australian Shelf observed remnants of mucoid domiciles still attached to specimens of both Julmarichardia gutui and Numbakulla pygmaeus Guţu & Heard, 2002 . Whether the mucus glands occurring in the representatives of these two small Indo-Pacific families are homologous or have been derived independently remains to be determined.