Basoniscidae, Wilson, 2024

Wilson, George D. F., 2024, A new family of Asellota (Crustacea, Isopoda) from the deep sea of Zealandia, European Journal of Taxonomy 917 (1), pp. 122-151 : 132

Family Basoniscidae fam. nov.

urn:lsid:zoobank.org:act:D809A180-3B53-44FD-BDB3-78985F61C923

Type genus Basoniscus gen. nov., monotypic.

Diagnosis

Head broad, without anteromedial rostral projections, antennal insertions separate (not adjacent), lateral margin linear, broadening posteriorly, without eyes or eye lobes. Pereion broad with tergal projections, medially vaulted but laterally flattened; without specialization of pereionites, without defined tagmosis; pereion lateral margins confluent with head and pleotelson margins. Pereionites free dorsally and ventrally, pereionite 1 and head articulated; pereionite 7 and pleotelson articulated. Coxae positions ventral, not visible dorsally, positioned midway between lateral margin and midline, not converging medially in posterior pereionites. Oöstegites developing internally before deploying at parturition. Cuticular organ (spermathecal duct) opening anterodorsally on pereionite 5, covered by pereionite margin. Penes emerging medially into male pleopod I, covered by pereionite 7 margin. Pleon single somite, all pleonites merged into pleotelson. Pleopodal chamber enclosed, positioned anterior to posterior margin. Anus ventral, with postanal margin. Clypeus anteriorly flattened, projecting to dorsal margin of head, dorsally angular. Labrum shallower and narrower than clypeus. Antennula shorter than width of head, basal article longer than broad, tapering distally. Antenna elongate, projecting anteriorly, podomere articles unmodified; article 3 longer than articles 1, 2 and 4, with convex margins, exopod single segment distally rounded with setae; flagellum first article single, unmodified (not conjoint or inflated). Mandible molar process cylindrical, two distal ridges of sharp denticles, spinulate spines posteriorly; incisor process not enlarged, with distal cusps only, left lacina mobilis distinct from spine row, right lacinia mobilis indistinguishable from spine row. Maxilliped endite with distomedial concavity; epipod projecting beyond palp insertion; palp article 2 narrow, article 5 longer than wide. Pereiopod I dactylar ventral claw robust, shorter and basally narrower than dorsal claw. Pereiopod II – VII dactylar ventral claw more robust than dorsal claw. Pleopod III eXopod uniarticulate, shorter than endopod, with fringe of fine setae laterally; endopod with 3 plumose setae, with large gap between medial seta and lateral two setae. Pleopod IV exopod uniarticulate, shorter than endopod, with distally narrowing margins. Uropod protopod broad, with medial lobe covering anus; endopod longer than protopod, rod-like, distally rounded; exopod, tiny, squat, on medial margin.