Allodiplophryxus unilateralis, An & Chen & Paulay, 2020

An, Jianmei, Chen, Ruru & Paulay, Gustav, 2020, Three new species of abdominal shrimp parasites (Crustacea: Isopoda: Bopyridae Hemiarthrinae) from the Indo-West Pacific, Zootaxa 4845 (2), pp. 264-274 : 266-267

publication ID	https://doi.org/ 10.11646/zootaxa.4845.2.7
publication LSID	lsid:zoobank.org:pub:ED92874B-EBFF-4A77-A9C8-B654F30BA28C
DOI	https://doi.org/10.5281/zenodo.4407329
persistent identifier	https://treatment.plazi.org/id/03808789-FFCF-A47F-FFCD-AB93C99A8013
treatment provided by	Plazi
scientific name	Allodiplophryxus unilateralis
status	sp. nov.

Treatment

Allodiplophryxus unilateralis View in CoL n. sp.

Fig. 1 View FIGURE 1

Material examined. Holotype female, ovigerous, 1.53 mm (maximum length, from anterior end of head to uropods), paratype male, 0.94 mm, WAM C75202 & C75203 (ex UF Arthropoda 23161), Australia, Western Australia, Ningaloo Reef, S shallow bommies, back reef, patchy corals on sand, in rubble 2–3 meters snorkel, by hand, 22.7415°S, 113.6836°E, coll., Robert Lasley , 15 May 2009. Infesting Jocaste lucina (Nobili, 1901) WAM C 75204 (ex UF Arthropoda 21490). GoogleMaps

Description. Holotype female (WAM C75202) length 1.53 mm, pleonal length 0.67 mm. Body outline oval, sinistrally distorted ( Fig. 1A, B View FIGURE 1 ).

Head subovate, embedded in pereon, not visible in dorsal view, covered by oostegite 2. Eyes not discernible ( Fig. 1A View FIGURE 1 ). Antennulae with two articles; antennae absent ( Fig. 1C View FIGURE 1 ). Right maxilliped articulated, anterior article triangular, much large than posterior one, without palp, plectron short and blunt, ( Fig. 1D View FIGURE 1 ). Anterior apex of left maxilliped rolled inward ( Fig. 1E View FIGURE 1 ). Barbula ( Fig. 1F View FIGURE 1 ) with 12 irregular marginal projections, as well as two pairs of short, blunt projections on raised layer.

Pereon with segments distinct on concave side only ( Fig. 1A View FIGURE 1 ). Pereomere 2 ventrally produced into several irregular fleshy projections ( Fig. 1B View FIGURE 1 ). First oostegite of two sides different, left ( Fig. 1G View FIGURE 1 ) much wider than right ( Fig. 1H, I View FIGURE 1 ); right with long, slender posterior part and internal ridge with two tubercles ( Fig. 1H, I View FIGURE 1 ); left with broad posterior part and internal ridge nearly entire ( Fig. 1H View FIGURE 1 ). Five pereopods discernible on short side, anterior two well developed, while posterior three small and clustered together. Three pereopods present on long side, first two well developed ( Fig. 1J View FIGURE 1 ), third represented only by scar-like basis.

Pleon of six pleomeres, first four bearing biramous lateral plates ( Fig. 1A View FIGURE 1 ), fifth with uniramous lateral plates, pleotelson small and globose, embedded into fifth pleomere ( Fig. 1K View FIGURE 1 ). Biramous pleopods present on first four pleomeres only, restricted to short side ( Fig. 1B View FIGURE 1 ).

Paratype male ( UF 23161 ) length 0.94 mm, maximum width (across pereomere 4) 0.39 mm, head length 0.18 mm, head width 0.25 mm, pleonal length 0.18 mm. Black pigmentation on dorsal surface of first pereomere and head .

Head oblong; black eyes near lateral margin ( Fig. 1L View FIGURE 1 ). Antennulae and antennae each with 3 articles ( Fig. 1M, N View FIGURE 1 ).

Pereon segments distinct ( Fig. 1L View FIGURE 1 ), with truncate margins and lacking midventral projections ( Fig. 1M View FIGURE 1 ). First three pereopods with large dactyli, decreasing in size posteriorly, last four pereopods with smaller dactyli; all dactyli sharp and pointed ( Fig. 1O, P View FIGURE 1 ). Carpi and meri of first pereopods larger than those of others ( Fig. 1M, O, P View FIGURE 1 ).

Pleon fused into single piece, but with obscure indentation demarcating first pleomere; narrower than the last pereomere ( Fig. 1M View FIGURE 1 ); with scattered black pigmentation on ventral surface. Pleopods and uropods absent.

Etymology. The specific name, unilateralis , refers to the restriction of pleopods to the short side of the body in the female.

Remarks. Species in four genera within the Hemiarthrinae have biramous lateral plates on the pleon: Allodiplophryxus , Diplophryxus , Micropodiphryxus , and Cataphryxus . The present specimens are placed in Allodiplophryxus because the female has biramous lateral plates and two prominent pereopods on the long side but five on the short side, and because the male has a fused pleon. The new species differs from the only congener, A. floridanus Markham, 1985 , in the following characters of the female (character states in A. floridanus given in parentheses): 1) pleon with six segments (five segments); 2) first oostegite asymmetrical (symmetrical); 3) pleopods restricted to short side (pleopods on both sides). The new species extends the range of Allodiplophryxus from the West Atlantic to the Indo-West Pacific.