Praedatrypaea orientalis (Bate, 1888) Poore, 2023

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 : 216-219

Praedatrypaea orientalis (Bate, 1888) comb. nov.

Figures 1e , 33 , 34

Cheramus orientalis Bate, 1888: 30 , pl. 1 fig. 2.— Tudge et al., 2000: 145.— Sakai, 2011: 370.—Holthuis, 1991: 239 (type species designation of Cheramus – q. v. above ).

Callianassa (Cheramus) orientalis .—Borradaile, 1903: 546.—De Man, 1928b: 9, pl. 1 fig. 2, 2a.—De Man, 1928a: 26, 93, 98, 119, 132, 137.

Callianassa orientalis . — Sakai, 1999: 49, fig. 5.— Sakai, 2005:20, 95.

Callianassa malaccaensis Sakai, 2002: 492–496 , figs 18, 19.— Sakai, 2005: 91–92. Syn. nov.

Cheramus malaccaensis . — Sakai, 2011: 368.

Pugnatrypaea orientalis .— Poore et al., 2019: 139, 143.

Material examined. Australia, NT, Arafura Sea, 9° 50.466' S, 135° 16.099'E, 80 m, muddy sand ( CSIRO stn SS05/2005/005/GR006), AM P.74440 (male, 5.9 mm) . 9° 22.63' S, 134° 12.83' E, 106 m, sandy mud ( CSIRO stn SS05/2005/015/GR025), AM P.74441A (male, 6.5 mm) . 9° 49.933'S, 135° 19.656'E, 83 m, calcareous mud ( CSIRO stn SS05/2005/008/GR013), AM P.74444 (female, 3.5 mm) . 9° 22.66' S, 134° 12.87' E, 70 m, sandy mud ( CSIRO stn SS05/2005/015/ BS004 ), AM P.74472 (male, 5.9 mm) . 9° 48.774'S, 135° 15.412' E, 82 m, ( CSIRO stn SS05/2005/010/GR017), AM P.74473 (female, 5.10 mm) . 9° 47.593'S, 135° 16.636' E, 85 m, muddy sand ( CSIRO stn SS05/2005/012/GR019), AM P.74476 (male, 3.5 mm; female, 3.3 mm) . 9° 47.992' S, 135° 22.001' E, 92 m, calcareous mud ( CSIRO stn SS05/2005/002/GR001), AM P.74477 (male, 4.9 mm) . 9° 50.361'S, 135° 20.904' E, 87 m, muddy sand ( CSIRO stn SS05/2005/006/GR008), AM P.74479 (female without chelipeds, 5.9 mm) ; 9° 47.986' S, 135° 22.007' E, 91 m, calcareous mud ( CSIRO stn SS05/2005/002/GR002), AM P.74449 (1 incomplete) ; 9° 47.768' S, 135° 16.935' E, 84 m, rippled sand ( CSIRO stn SS05/2005/011/GR018), AM P.74446 (2 females, incomplete, 3.1, 3.9 mm) .

Diagnosis. Antennular peduncle reaching midpoint of antennal peduncle article 5. Maxilliped 3 ischium about twice as long as wide; merus oval, about as wide as long, without tooth on oblique margin. Chelipeds meri upper margins each unarmed. Major cheliped merus lower margin with spine at midpoint and few smaller proximal teeth in female, with spine at midpoint or row of teeth in male; carpus about as long as wide or longer than wide; palm 1.25 times as long as carpus, 1.2 times as long as wide; fingers, cutting edges with obsolete teeth in female, with irregular teeth in male. Uropod endopod 1.6 times as long as wide; anterior margin straight, with 5 distal spiniform setae; distal-posterior margin strongly convex distally; dorsal face with row of 5 spiniform setae close to anterior margin. Uropod exopod rectangular, truncate distally, 1.5 times as long as wide; anterior margin straight, not setose. Telson 1.15 times as long as wide, widest at strong lateral lobes at one-third length; posterior margin with shallow medial depression, with medial spine; with 2 pairs of spiniform setae on posterolateral margins. Male pleopod 1 2-articled; pleopod 2 biramous.

Supplementary description. Male. Rostrum acutely triangular in dorsal view, situated at level of dorsal carapace, 0.8 length of eyestalks. Carapace dorsally flat, as long as pleomeres 1–3 combined; orbital margin oblique; anterolateral lobes rounded; subanterolateral margin oblique; cervical groove across 0.75 length of carapace, shallow at midpoint, almost reaching linea thalassinica.

Eyestalk 1.2 times as long as wide, almost quadrantshaped in dorsal view, with oblique dorsal face diverging from rostrum, anterolateral margin concave, anteromedial angle rounded in dorsal view, nearly reaching distal margin of antennular peduncle article 1. Cornea densely pigmented, sitting near middle of eyestalk.

Antennular peduncle reaching near midpoint of antennal peduncle article 5; article 1 barely visible in dorsal view; article 3 longer than articles 1 and 2 combined; articles 2 and 3 with longitudinal ventral row of long setae.

Antennal peduncle article 5 0.6–0.7 length of article 4; scaphocerite comma-shaped in dorsal view.

Maxilliped 3 ischium almost parallel-sided over most of length, twice as long as wide, crista dentata consisting of row of about 20 uneven contiguous teeth; merus 0.6 length of ischium measured along outer margin, about as wide as long, with mesiodistal margin convex, oblique, without tooth; carpus little shorter than merus outer margin; propodus tapering, 1.4 times as long as greatest width; dactylus 0.75 length of propodus, elongate-oval, with dense row of short setae along flexor (lower) margin.

Pereopods 1 (chelipeds) unequal, dissimilar. Major cheliped carpus-palm upper margin 0.9 carapace length. Ischium expanding distally, upper margin unarmed; lower margin with 6 similar spines over middle third. Merus as long as ischium, 1.8 times as long as wide; upper margin convex; lower margin convex, with spine at midpoint or with 7 evenly spaced spines. Carpus about as long as wide. Propodus upper margin 1.2 times as long as carpus; palm about as long as wide; upper margin convex; lateral surface smooth, convex; mesial surface convex, with blunt boss or bifid tooth proximal to gape; lower margin with row of setae extending onto fixed finger; fixed finger two thirds as long as palm; cutting edge with irregular teeth over proximal half. Dactylus as long as fixed finger, curved; cutting edge with broad subproximal tooth, irregular crenellations over middle third.

Minor cheliped carpus-palm upper margin 0.65 carapace length. Ischium lower margin with minute teeth. Merus as long as ischium; upper margin convex, smooth; lower margin with tooth beyond midpoint. Carpus dilating, 1.6 times as long as merus, about 4 times as long as wide. Palm 0.4 times as long as carpus, 1.5 times long as wide; upper margin barely convex; lower margin carinate, with row of setae extending onto fixed finger; fixed finger longer than palm, cutting edge smooth. Dactylus about as long as palm, curved; cutting edge smooth.

Pereopod 2 merus 3.3 times as long as wide; carpus 1.7 times as long as wide; chela subtriangular; palm twice as wide as upper margin; dactylus 2.8 times as long as palm upper margin. Pereopod 3 carpus oval, 2.4 times as long as wide; propodus oval, 1.7 times as wide, with evenly curved lower margin, marginal setae in groups separated by gaps, with 1 short spiniform seta; dactylus 0.75 length of propodus upper margin. Pereopod 4 propodus longer than carpus, with dense grooming setae distally on lower margin, scattered stiff setae on outer surface, with short spiniform setae at base of dactylus; dactylus half as long as propodus. Pereopod 5 chelate.

Male pleopod 1 short, narrow. Pleopod 2 with endopod shorter than exopod.

Uropod endopod and exopod reaching posterior margin of telson. Endopod suboval, 1.6 times as long as wide; anterior margin almost straight; anterodistal margin setose, with 5 subdistal spiniform setae; posterior margin with marginal setae; dorsal face with row of 5 well-spaced short setae close to anterior margin. Exopod rectangular, truncate distally, 1.5 times as long as wide; anterior margin straight, not setose; posterior margin with 9 falcate setae indistinguishably merged with densely setose distal margin; dorsal plate scarcely indistinguishable from distal margin, comprising short and medium stiff setae merging anteriorly with similar setae on distal margin; dorsal face without spiniform setae.

Telson 1.15 times as long as wide, widest at strong lateral lobes at one third length, narrowing posteriorly without angle to paired convex posterior margin with medial notch bearing medial spine; with 2 pairs of spiniform setae on posterolateral margin; lateral lobe with 2 short setae posterior; transverse dorsal ridge with long setae.

Variation. The major cheliped of smaller males is less well developed, narrower and with obsolete teeth on the fingers (cf. fig. 34m with fig. 34g, k). The major cheliped merus of the two largest males differ, one with a row of teeth along the lower margin, the other with one prominent tooth and minute teeth (cf. fig. 34g, o). The major cheliped of the female has fewer teeth on the lower margin of the merus and simpler dentition on the fingers (fig. 34c, d).

Distribution. Sahul Shelf ( Australia, NT, Arafura Sea); 51– 106 m.

Remarks. The holotype of Cheramus orientalis Bate, 1888 is from the eastern Arafura Sea (9° 59' S, 139° 42' E, 28 fm [51 m]), very close to this new collection. Bate’s description and figures are sketchy and can not be relied on. W. T. Calman’s figures of the telson, uropod and maxilliped 3 of the holotype were included in De Man (1928a) and the carapace, pleomere 6, telson and uropod of the holotype were figured by Sakai (1999); all figures are consistent with the new material. Bate’s holotype lacks chelipeds and other pereopods which are described and figured here. Cheramus orientalis Bate, 1888 was listed by Poore et al. (2019) as a member of Pugnatrypaea , mainly because it lacks the tooth on the merus of maxilliped 3 present in other species of Praedatrypaea . The telson does not have the deep posterior notch characteristic of Pugnatrypaea . Illustrations of Pugnatrypaea ruiyui Liu, 2022 , from the northern South China Sea, are virtually identical to those of Praedatrypaea orientalis presented here. For the time being, it is treated as Praedatrypaea ruiyui (Liu, 2022) comb. nov.

Callianassa malaccaensis Sakai, 2002 is probably a synonym of P. orientalis . Sakai (2002) recognised the similarity between the two species, noting only slight differences in the relative lengths of the antennular and antennal peduncles and shape of the uropodal exopod, differences that appear within species variability. The telson, uropod, maxilliped 3, eyestalk, and antennae are quite similar. If so, the species range would extend into the Andaman Sea at similar depths.

Figures

Figure 1. Dactylus of maxilliped 3 of representatives of two callianassoid families. Eucalliacidae. a, Calliaxina kensleyi (Dworschak, 2005), MNHN IU-2016-8084. Callianassidae. b, Caviallianassa moorea sp. nov., UF 28875; c, Paratrypaea sp, MNHN IU-2013-7035; d, Praedatrypaea lobetobensis sp. nov., MNHN IU-2015-109; e, Praedatrypaea orientalis (Bate, 1888), AM P.74473; f, Rayllianassa amboinensis (De Man, 1888), UF 8700; g, Rayllianassa bifida sp. nov., MNHN IU-2013-7137; h, Rudisullianassa pandan sp. nov., MNHN IU-2013-7063; i, Rudisullianassa rudisulcus Komai, Fujita and Maenosono, 2014, MNHN IU-2013-7121; j, Scallasis amboinae Bate, 1888, MNHN IU-2013-12303; k, Spinicallianassa spinicauda (Komai, Maenosono and Fujita, 2014), MNHN IU-2014-2778; l, Spinicallianassa papetoai sp. nov., UF 29280.

Figure 33. Praedatrypaea orientalis (Bate, 1888). Australia, Arafura Sea. AM P.74479, female, 5.9 mm: a, antennular, antennal peduncles, eyestalk, carapace, pleon, uropod (lateral); b, antennular, antennal peduncles, eyestalk, carapace (dorsal); c, telson, right uropod (setae not figured); d, maxilliped 3 (inner face); e–h, pereopods 2–5; i–k, pleopods 1–3. Scale bars = 1 mm.

Figure 34. Praedatrypaea orientalis (Bate, 1888). Australia, Arafura Sea. AM P.74444, female, 5.9 mm: a, antennular, antennal peduncles, eyestalk, carapace (lateral); b, antennular, antennal peduncles, eyestalk, carapace (dorsal); c, major cheliped (right, mesial); d, major cheliped fingers (lateral); e, minor cheliped (left, mesial). AM P.74440, male, 5.9 mm: f, pleomere 6, telson, right uropod; g, major cheliped (left, mesial); h, major cheliped fingers (lateral); i, minor cheliped (right, mesial); j, pereopod 5 coxa (mesial); k, l, pleopods 1, 2. AM P.74476, male, 3.5 mm: m, major cheliped (left, mesial); n, minor cheliped (right, mesial). AM P.74472, male, 5.9 mm: o, major cheliped (left, mesial); p, major cheliped fingers (lateral). Scale bars = 1 mm.