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

Poore, Gary C. B., 2023, New records, one new genus and 21 new species of Callianassidae (Crustacea, Axiidea) from the Indo-West Pacific, Memoirs of Museum Victoria 82, pp. 167-255 : 203-204

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

Praedatrypaea Poore et al., 2019: 97 .— Robles et al., 2020: figs 1,

3, 6.— Poore and Ahyong, 2023: 213.

Diagnosis. Rostrum acute, anteriorly directed, usually shorter than eyestalks. Pleomere 1 tergite divided into 2 sections by transverse step. Pleomere 6 with sublateral ventral sharp ridge, flared posteriorly (where observed). Antennular peduncle exceeded by all or at least half of antennal peduncular article 5; articles 2 and 3 with single lateral row of well-spaced long setae along lower margin. Antennal scaphocerite simple, longer than wide, acute. Maxilliped 3 merus wider at ischium-merus suture than long, with or without distal spine on distal free margin. Male major cheliped merus smooth or with tooth at midpoint or with row of teeth along lower margin. Pereopod 3 propodus oval, lower margin slightly convex, leading to narrow sharply rounded proximal lobe. Uropodal endopod ovoid, longer than wide, anterior margin straight, posterodistal margin evenly convex, usually with spiniform setae near anterior and distal margins. Uropodal exopod about 1.5–1.8 times as long as wide, distal margin clearly differentiated from anterior margin, anterodistal corner right-angled, posterodistal margin with row of 6–8 long blade-like setae proximal to long setae on distal margin. Telson anterolateral lobe prominent, defined posteriorly by clear unchitinised region; posterior margin convex between posterolateral angles or with medial notch, with medial spine.

Remarks. Members of Praedatrypaea are recognised by the weak calcification between the anterolateral lobe and the remainder of the telson (fig. 27e, f), the prominent posterior median spine on the telson sitting in a shallow concavity (e.g. fig. 28d) or not (fig. 27d), and the lower margin of the merus of the chelipeds with one tooth at its midpoint (rarely more). Most species possess a tooth on the distal margin of the merus of maxilliped 3 (e.g. fig. 27h).

Robles et al. (2020) found three well-separated species ( P. praedatrix [De Man, 1905], P. propinqua [De Man, 1905] and P. MOZ-34) to belong to a clade sister to all other callianassid genera. Poore et al. (2019) included the two described species plus P. modesta (De Man, 1905) and P. longicauda ( Sakai, 1967) , all originally described from Indonesia, in Praedatrypaea . Praedatrypaea praedatrix and P. propinqua have been recorded from localities other than from their type localities; both have been recorded from the North West Shelf of Australia and another new species described herein occurs there. A second species of Praedatrypaea from Mozambique represented by a single small individual without chelipeds is also described below. Praedatrypaea modesta is diagnosed below. In P. longicauda the distal tooth on maxilliped 3 is obsolete, but is otherwise too poorly known to be diagnosed or included in the key to species below.

All these species have a tooth on the merus of maxilliped 3. Three species lacking the maxillipedal 3 meral tooth included in Pugnatrypaea by Poore et al. (2019) are here transferred to Praedatrypaea : P. orientalis (Bate, 1888) comb. nov., P. intermedia (De Man, 1905) comb. nov. and P. lobetobensis (De Man, 1905) comb. nov. All possess a weakly chitinised suture isolating the anterolateral lobe of the telson and a row of teeth along the lower margin of the major chelipeds, similar to other species. In addition, P. ruiyui (Liu, 2022) comb. nov., described from the northern South China Sea, is transferred from Pugnatrypaea , in which it was originally included, for the same reasons. From its illustrations, the species is difficult to distinguish from P. orientalis .

These transfers bring to 13 the number of named species of Praedatrypaea . The genus varies in other ways besides the presence or absence of a meral tooth on maxilliped 3. The posterior margin of the telson ranges from convex to having a medial excavation, and the lower margin of the cheliped merus may have a single tooth at the midpoint or a row of teeth. This variability makes distinction from species of Pugnatrypaea difficult – Pugnatrypaea is restricted here to species with a basal spine on the merus of the major cheliped. In the light of this rearrangement, the diagnosis of the genus has been updated.

The telson and uropod of Notiax bicauda Sakai, 2010 from the Gulf of Tonkin, also included in Pugnatrypaea by Poore et al. (2019), are consistent with Praedatrypaea but its chelipeds are unknown. It remains a species inquirenda.

Key to ten species of Praedatrypaea ( P. bicauda , P. inhambane and P. longicauda excluded)

1. Chelipeds with proximal tooth on upper margin of merus 2

– Chelipeds without proximal tooth on upper margin of merus 3

2. Telson with convex lateral margins converging on pair of lobes (each as long as wide) separated by narrow median notch. Pereopod 3 propodus oval, 1.6 times as long as wide

P. lobetobensis

– Telson with straight lateral margins converging on pair of lobes (each shorter than wide) separated by concave median notch. Pereopod 3 propodus elongate-oval, twice as long as wide P. intermedia

3. Maxilliped 3 merus without tooth on distal margin P. orientalis / P. ruiyui

– Maxilliped 3 merus with tooth on distal margin 4

4. Pereopod 3 propodus linear (4 times as long as wide). Major cheliped fingers with irregular teeth along cutting edges. Uropodal endopod with 3 long spiniform setae close to distoposterior margin P. modesta

– Pereopod 3 propodus oval (2–4 times as long as wide). Major cheliped fingers with 1 tooth or smooth on cutting edge. Uropodal endopod without 3 long spiniform setae close to distoposterior margin (setae arranged otherwise) 5

5. Antennular peduncle reaching to end of antennal peduncle article 5. Telson as long as wide; anterolateral lobes near midpoint P. mandu

– Antennular peduncle reaching to end of antennal peduncle article 4 or midway along article 5. Telson longer than wide; anterolateral lobes proximal to midpoint 6

6. Major cheliped carpus twice as long as wide P. ningaloo

– Major cheliped carpus about as long as wide 7

7. Uropodal exopod rectangular, 1.6–1.9 times as long as wide P. propinqua

– Uropodal exopod rectangular-oval, 1.4–1.5 times as long as wide 8

8. Telson 1.3 times as long as wide, posterior margin medially concave P. praedatrix

– Telson 1.2 times as long as wide, posterior margin convex P. jangamo