Arenallianassa Poore, Dworschak, Robles, Mantelatto and Felder, 2019

Schnabel, Kareen E., Rowden, Ashley A. & Poore, Gary C. B., 2023, A new species of Arenallianassa (Decapoda: Axiidea: Callianassidae) from hydrothermal vents with notes on its ecology and a redescription of Arenallianassa arenosa (Poore, 1975), Memoirs of Museum Victoria (Mem. Mus. Vic.) 82, pp. 55-69 : 58

Arenallianassa Poore, Dworschak, Robles, Mantelatto and Felder, 2019

Arenallianassa Poore et al., 2019: 91 .— Robles et al., 2020: 118, 128, figs 1 , 3, 6, 8 .

Diagnosis. Rostrum obtusely triangular, flat, not reaching cornea. Pleomere 1 tergite with weak transverse ridge. Maxilliped 3 merus wider at ischium-merus suture than long. Male major cheliped merus with prominent truncate or oval hook armed with serrations along lower margin, excavate laterally at base; carpus and propodus flattened, upper and lower margins carinate, blade-like, submarginal mesial face especially of carpus deeply concave; propodus distal margin with deep notch at base of fixed finger. Pereopod 3 propodus rectangular or oval, with broadly rounded free proximal lobe. Male pleopod 2 absent. Uropodal endopod ovoid, longer than wide, anterior margin straight or slightly convex, posterodistal margin evenly convex, with few facial distal spiniform setae; exopod distal margin clearly differentiated from anterior margin, anterodistal corner right-angled. Telson lateral margins convex, subparallel or tapering distally (amended from Poore et al. 2019).

Remarks. The genus is diagnosed by the combination of a blade-like meral hook with serrate margins on the major cheliped of both sexes, an ovoid uropodal endopod, little longer than wide, and a telson that is about as wide as long with rounded posterolateral corners ( Poore et al., 2019). With the addition of A. katrinae sp. nov. the diagnosis is adjusted to consider the different shapes of the pereopod 3 propodus, the distribution of spiniform setae on the uropodal endopod and the difference in the shape of the telson.

Poore’s (1975) and (2004) illustrations of A. arenosa were basic but enabled him to distinguish the species from other Australian callianassid species. Subsequent observations presented in the supplementary description and figures below show the setae on the telson and uropod, notably the distal transverse row of short spiniform setae on the face of the uropodal endopod, a feature in one form or another shown by Poore et al. (2019) and Robles et al. (2020) to be shared with Filhollianassa , Notiax Manning and Felder, 1991 , Paratrypaea , Trypaea Dana, 1852 and Tastrypaea Poore, Dworschak, Robles, Mantelatto and Felder, 2019 .

Figures

Figure 1. Neighbour-joining consensus tree inferred from the 16S rRNA gene sequences for eight species of Callianassidae. Genbank Accession numbers are appended. Consensus support (%) based on 1000 bootstrap replicates is shown for each node. Scale indicates patristic distances.

Figure 8. Seafloor images taken by NIWA’s Deep-Towed Imaging System (DTIS) camera sled during 2010 RV Kaharoa voyage to the Bay of Plenty. a, North Calypso Vent, stn KAH1004/5, approx. depth 175 m; b, South Calypso Vent, stn KAH1004/8, approx. depth 195 m; c, Moutohorā/Whale Island, stn KAH1004/12, 20–30 m depth; d, Whakaari/White Island, stn KAH1004/14, approx. 225 m depth. Scale bars = 200 mm.