Arenallianassa arenosa ( Poore, 1975 )

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 : 58-61

Arenallianassa arenosa ( Poore, 1975)

Figures 2 , 3

Callianassa arenosa Poore, 1975: 197–201 , figs 1 , 2.— Poore and Griffin, 1979: 250, figs. 15–17.— Sakai, 1988: 57.— Sakai, 1999: 39.— Sakai, 2005: 73.

Biffarius arenosa .— Tudge et al., 2000: 142.

Biffarius arenosus .— Boon et al., 1997: 503–511 (diet).— Bird et al., 1999: 523–532 (sediment transport).— Bird and Poore, 1999: 77– 87 (burrow morphology).— Davie, 2002: 457.— O’Hara, 2002: 680.— Poore, 2004: 181, fig. 49b, d, pl. 12a.— Butler et al., 2009: 43–59 (population biology).

Trypaea arenosa .— Sakai, 2011: 391.

Arenallianassa arenosa .— Poore et al., 2019: 91, 136, 142.— Robles et al., 2020: figs 1 , 3, 6.

Material illustrated. Australia, Victoria, Tooradin, 38.22° S, 145.37° E, NMV J16708 (male, cl 6.9 mm). Cannons Creek , 38.25° S, 145.32° E, NMV J16670 (female, cl 7.3 mm). Sandringham, 37.5° S, 144.99° E; NMV J31887 (male, not measured) . Queensland, Conway Beach, Prosperine , 20.48° S, 148.75° E; NMV J16726 (male, cl 5.1 mm) . Northern Territory, Gove , 12° 12’ S, 136° 43’ E; NTMAG Cr009860 (female, cl 5.3 mm, with Bopyridae in branchial cavity) .

Types. Australia, Victoria, Port Phillip Bay, 3.5 km off Seaford , 13 m, sandy sediment, 8 Sep 1971 ( PPBES station 951). Holotype: NMV J271 , female, tl 24 mm. Paratypes: NMV J272 , male, tl 22 mm; NMV J273 , 10 specimens .

Diagnosis. Male major cheliped merus lower margin with strong proximal truncate tooth, its apex directed distally, margins serrate, plus low denticulate convex blade beyond midpoint. Minor cheliped merus lower margin with spine at midpoint. Pereopod 3 propodus oval. Telson with convex parallel lateral margins.

Supplementary description. Carapace 0.24 total length; with distinct linea thalassinica, with defined dorsal oval marked posteriorly by shallow transverse cervical groove (at 0.8 cl) extending anteroventrally to each side above linea thalassinica as shallow groove; frontal margin scarcely oblique, anterolateral lobe obsolete. Rostrum convex in lateral view, broadly triangular, reaching halfway to cornea. Pleonites 1 and 2 together as long as carapace; ratio of lengths of pleonites 2–6 – 1: 0.8: 0.7: 1: 1.

Antennular peduncle 0.5 times carapace length, article 3 2.3 times as long as article 2, with ventrolateral row of long setae. Antennal peduncle almost as long as antennular peduncle; article 5 0.75 times as long as article 4; scaphocerite semicircular. Maxilliped 3 ischium 1.2 times as long as wide, dilating distally; crista dentata curved, of about 15 sharp spines, not overlapping ischium-merus suture; merus semicircular, 1.8 times as wide as long, distal margin curved beyond base of carpus; propodus 1.8 times as long as wide, flexor margin almost straight; dactylus with convex extensor margin, flexor margin with dense setal brush over distal half.

Pereopods 1 (chelipeds) unequal, dissimilar, sexually dimorphic. Male major cheliped carpus-palm (fingers of chelae not included) 1.6 times carapace length; ischium slender, lower (flexor) margin with 2 proximal denticles; merus body twice as long as wide, upper margin with 5 proximal tubercles, lower margin with strong proximal truncate tooth (meral hook), its apex directed distally, margins serrate, plus low denticulate convex blade beyond midpoint, lateral face with deep welldefined excavation at base of tooth; carpus as wide as long, upper and lower margins carinate, rolled mesially; propodus upper margin 1.3 times as long as carpus, 1.1 times as long as greatest width, lower margin of palm carinate; palm distomesial margin with denticulate tubercle at base of fixed finger, strongly excavate between tubercle and fixed finger and mesially; fixed finger 0.4 length of lower margin, almost conical; dactylus 0.75 as long as upper margin of palm, cutting edge with blunt tooth in proximal third, another near midpoint, with acute reflexed tip. Minor cheliped carpus-palm about as long as carapace; palm 0.3 times width of major; ischium narrow, unarmed, longer than merus; merus twice as long as wide, lower margin with spine at midpoint; carpus 1.5 times as long as merus, 2.3 times as long as wide, parallel-sided over distal half; palm upper margin 0.55 times as long as carpus, 1.2 times as long as wide, lower margin as long as carpus; fixed finger evenly tapering, half-length of lower margin, cutting edge smooth; dactylus curved, cutting edge unarmed.

Female major cheliped carpus-palm 1.3 times carapace length; ischium slender, lower (flexor) margin with obsolete proximal denticles; merus essentially as in male; carpus 1.3 times as long as wide, upper and lower margins carinate, rolled mesially; propodus upper margin 0.9 times as long as carpus, 1.2 times as long as greatest width, lower margin of palm carinate; palm distomesial margin with denticulate tubercle at base of fixed finger, with shallow notch between tubercle and fixed finger; fixed finger 0.4 length of lower margin, almost conical, cutting edge minutely denticulate proximally; dactylus 0.8 times as long as upper margin of palm, cutting edge convex, with acute reflexed tip.

Pereopod 2 chelate; carpus 1.7 times as long as wide; palm twice as wide as upper margin. Pereopod 3 propodus with evenly convex lower margin, proximally reaching lower margin of carpus, almost truncate distally, 1.4 times as long as wide at midlength, with spiniform seta on flexor margin, near distal end, buried among finer setae. Pereopod 4 simple, propodus densely setose laterally. Pereopod 5 chelate, propodus and dactylus densely setose.

Male pleopod 1 of 2 simple articles; article 2 1.7 times as long as article 1. Male pleopod 2 absent.

Uropodal endopod 1.1 times as long as wide, anterior margin gently convex, ending at rounded right angle with distal margin; distal and posterior margins indistinguishable; margins setose; with dorsal cluster of spiniform setae (usually 3 close together) near anterodistal margin; exopod as wide as anterior margin, anterior margin almost straight, posterodistal margin evenly curved, dorsal plate extending more than half width of exopod, slightly differentiated from distal margin, bearing spiniform setae overlapping setose margin.

Telson slightly wider than long, broadest proximally, tapering to rounded posterolateral corners, posterior margin convex; dorsal surface with c. 5 pairs of fine setae near midpoint.

Distribution. Eastern Australia (Gove, Northern Territory, to eastern Tasmania); marine and estuarine bays: intertidal to 25 m.

Remarks. Arenallianassa arenosa is possibly the most common callianassid in south-eastern Australia. Its ecology has been much studied ( Poore, 1975; Coleman and Poore, 1980; Boon et al., 1997; Bird and Poore, 1999; Bird, 2000; Stapleton et al., 2001; Butler and Bird, 2007, 2008; Butler et al., 2009), mostly incorrectly treated as a species of Biffarius Manning and Felder, 1991 . Collections in Museums Victoria and the Australian Museum contain hundreds of specimens, mostly from intertidal or shallow beaches or mudflats close to Sydney and Melbourne, of which a few were re-examined here. The record from Gove, Northern Territory, is exceptional; otherwise, the northern-most record is from central Queensland.

The species is separated from other callianassids in Australia by the combination of the telson having convex parallel sides, the broad uropodal rami, operculiform maxilliped 3 with narrow propodus, and the shape of the major cheliped. The distal transverse row of short spiniform setae on the face of the uropodal endopod usually comprises three setae but more can be found sometimes (compare figs 2h, i, j).

Differences from A. katrinae sp. nov. are discussed under the species below.

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 2. Arenallianassa arenosa (Poore, 1975). NMV J16708 (male, cl 6.9 mm): a, carapace, pleon, telson, dorsal view; b, c, anterior carapace, eyestalk, antennule, antenna, dorsal view (only left appendages shown in b); d, telson, right uropod, dorsal view; e, maxilliped 3, mesial view; f, same, distal articles, lateral view; g, pleopod 1, lateral view. NTMAG Cr009860 (female, cl 5.3 mm): h, telson, left uropod, dorsal view. NMV J31887 (male); i, left uropod, anterodistal angle of endopod. NMV J16726 (male, cl 5.1 mm); j, left uropod, anterodistal angle of endopod. Scale bars = 1 mm.

Figure 3. Arenallianassa arenosa (Poore, 1975). NMV J16708 (male, cl 6.9 mm): a, major (right) cheliped, mesial face; b, major cheliped fingers, lateral face; c, merus, lateral face; d, minor (left) cheliped, lateral face; e, minor cheliped fingers, mesial face; f, pereopod 2; g, pereopod 3; h, pereopod 4; i, pereopod 5. NMV J16670 (female, cl 7.3 mm); j, major (right) cheliped, lateral. NMV J16726 (male, cl 5.1 mm); k, major (left) cheliped, mesial; l, major cheliped fingers, lateral. Scale bars = 2 mm.