Neaxius acanthus
Creators: name: Poore, Gary C. B.
name: Dworschak, Peter C.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Strahlaxiidae
Neaxius
Neaxius acanthus

description: Neaxius acanthus (A. Milne Edwards, 1879)
Figures 1–5, 8a–f
Axia acantha A. Milne-Edwards, 1879: 110.
Eiconaxius acanthus.— De Man, 1896: 491–497.—De Man, 1898: 700, pl. 34 fig. 57 (West-Celebes = Indonesia, Sulawesi).
Eiconaxius taliliensis Borradaile, 1900: 420–421, fig. 15a–c.
Axius acanthus.— Borradaile, 1903: 537 (listed as type species of Neaxius).
Axius taliliensis. — Borradaile, 1903: 537 (as synonym of Axius (Neaxius) acanthus A. Milne-Edwards, 1879).
Axius acanthus var. mauritiana Bouvier, 1914: 704.
Axius (Neaxius) acanthus var. mauritianus. — Bouvier,1915: 196– 198, fig. 7.— Fourmanoir, 1955 31, fig. 4.—De Man, 1925c: 3, 10, 14.
Axius (Neaxius) acanthus.— De Man, 1925a: 50–55.—De Man, 1925c: 3, 14 (part).— Poore and Griffin, 1979: 235–236, fig. 7 (Qld, Australia).— Tirmizi, 1983: 85–88, figs 1, 2 (Maluku, Indonesia).— Holthuis, 1953:51 (Marianas Is, Saipan).— Miyake, 1982: 93 (Japan).— Sakai, 1987: 303, 304 (Japan).
Neaxius acanthus.— Sakai and de Saint Laurent, 1989: 30–31.— Mukai and Sakai, 1992: 47–52, fig. 1 (Papua New Guinea).— Sakai, 1994: 200.— Kensley et al., 2000: 212, figs 5, 7F (Taiwan).— Kensley, 2003: 383 (Guam).— Kneer, 2006; Kneer, Asmus, Ahnelt and Vonk, 2008; Kneer, Asmus and Vonk, 2008 (Bone Batang I., S Sulawesi, Indonesia).— Sakai and Sawada, 2006: 1357 (Japan).— Tsang et al., 2008: 218–219 (Taiwan).— Tan et al., 2017: 5 (comment on name).
Neaxius glyptocercus.— Sakai, 2011: 326–331 (part) figs 61B, 62C, D (not figs 61A, C–E, 62A, B, E, F [interchanged with 61B]), = N. glyptocercus (von Martens, 1868.— Lin et al., 2012: 2–9 (Taiwan, misidentification).— Anker et al., 2015: 335, figs 25, 26.— Sakai, 2017: 188, fig. 3A.
Type material examined. Lectotype of Axia acantha. New Caledonia. MNHN IU-2014-11315 (Th812) (female, tl 72 mm, dry). Paralectotype, MNHN IU-2014-11316 (Th190) (male, cl 27 mm) (Fig. 1).
Syntypes of Axius acanthus mauritiana. Mauritius. Le Chaland, MNHN IU- 2014-11317 (Th191), ovigerous female, tl 69 mm (Bouvier, 1915, listed 2 specimens from this locality). Port Louis, MNHN IU-2014 -11318 (Th192), 1 male, tl 58 mm; 2 ovigerous females, tl 67, 62 mm (as listed by Bouvier, 1915) (Fig. 2).
Syntypes of Eiconaxius taliliensis. Papua New Guinea, New Britain, Talili Bay, UMZC I.57590 (male, 22.3 mm; ovigerous female, 19.4 mm) (Fig. 3).
Other material examined. Specimens marked * were listed by Sakai and de Saint Laurent (1989).
Tanzania. Mombasa, Levin Reef, MNHN IU- 2016-8073 (Th780*) (1 individual).
Madagascar. Nosy Iranja, IU-2014-22792 (Th 454*) (1 individual). Nosy Bé, IU-2014-22793 (Th 456*) (2 individuals); IU-2016-8071 (Th 455*) (3 individuals); NHMW 19385 (male, 26.3 mm, broken); NHMW 19386 (1 male, 24.5 mm, telson damaged); NHMW 19387 (fragments of 2 specimens); NHMW 24999 (female, 23.7 mm + exuvia). Nosy Bé, Palm Beach Hotel Bay, sand between coral rubble, 3 m. Sainte Luce, W of Ilot Babet, 24° 46.2' S, 47° 12.4' E, 1–10 m (ATIMO VATAE stn TA63) IU-2010-4331 (1 damaged individual).
Glorieuse Is, Grande Glorieuse I., IU- 2016-8072 (Th451*) (1 individual).
Mayotte. IU- 2014-22789 (Th1565) (1 individual); IU- 2014-22790 (Th1564) (1 individual).
Indonesia. Sulawesi, Bone Batang I., NHMW 25859 (male, 10.3 mm). Bali, Nusa Dua, intertidal seagrass, NHMW 25854–25858 (male 15.3 mm; 4 juveniles, 7.1–11.1 mm).
Papua New Guinea. Central Province, Motupore I., 09° 32' S, 147° 17' E, NMV J17235 (3 males, 21.9–27.5 mm; 2 ovigerous females, 20.3, 27.5 mm). Madang Province, Jais Aben Resort, Riwo, seagrass, 05° 09' S, 145° 48.2' E, 1–3 m (PAPUA NIUGINI stn PR195-A), MNHN not registered (photo only seen).
Malaysia. Sipadan, IU- 2016-8070 (1 individual).
Palau. ZMH K8411 (female, 17.1 mm).
Philippines. Bohol, Panglao I., Balicasag I., NMCR 39107 (25.8 mm); NHMW 25860 (male, 25.7 mm); ZRC 2017.0415 (male, 15.5 mm); ZRC 2017.0416 (male, 17.4 mm); MNHN-2016-3495 (male, 20 mm); NMCR 39108 (female, 20.6 mm). Momo Beach, 9° 36.1' N, 123° 45.2' E, NHMW 25861 (male, 20 mm); NHMW 25862 (male, 25.8 mm). Looc, sand and seagrass with coral patches, 9° 35.7' N, 123° 44.4' E, 4 m, NHMW 25863 (male, 19.5 mm).
Taiwan, Pingtung County, Banna Bay, 10 m, NHMW 25919 (male, 10.4 mm), NHMW 25923 (juvenile, 7.1 mm).
Japan. Ryuku Is., Ishigakaki I., IU- 2016-8078 (Th865*) (9 individuals); IU- 2016-8075 – 8077 (3 dry individuals).
New Caledonia. IU- 2016-8080 (Th511*) (13 individuals). Bourail, IU- 2016-8074 (Th1488) (1 individual). Ouano Plage, IU- 2014-22791 (Th1486) (1 individual).
Diagnosis. Carapace supra-antennal margin without anteriorly directed spine; anterolateral margin with 6 (4, 5) prominent spines, dorsalmost anteriorly directed; branchiostegite anterior margin unarmed; cervical groove with 4 (0–7) sharp spines along posterior margin. Telson 1.3–1.5 times as wide as long; tapering strongly from widest point to posterior margin, posterior margin about half greatest width; anterior transverse ridge straight, curving laterally but not reaching lateral margin at its widest point; posterior transverse ridge situated at 0.35– 0.4 distance between anterior ridge and posterior margin; posterolateral margin with 2–6 obsolete submarginal tubercles; posterior face concave, with obsolete third transverse ridge, with pair of sublateral longitudinal ridges subtended from ends of second transverse ridge, each with 2 (1–3) rounded tubercles, sometimes obsolete. Antenna article 2 with 1 (2) upper-mesial spine, 3 (0–6) lateral spines; scaphocerite with 1 (2) mesial sharp spine, 5 (2–6) sharp ventral spines; article 4 lower margin with 3 (0–5) sharp spines. Cheliped merus, lower margin with 4 (2–5) spines, lateral face with curved row of 8 (5–10) spines. Pereopod 2 merus, lower margin with row of 10 (8–17) spines. Pereopod 3 merus, lower margin without row of spines.
Remarks. A. Milne-Edwards (1879) did not specify how many specimens he had. Two remain in MNHN, one of which Sakai and de Saint Laurent (1989) called the type. This was an effective lectotype designation. This and many more from New Caledonia were examined.
Bouvier (1914, 1915) distinguished his variety from Mauritius, Axius acanthus mauritianus, on differences in the denticulation of the median rostral ridge, the number and nature of the spines on the anterolateral margin of the carapace and cervical groove, spination of the merus of the cheliped, and ornamentation of the pleonal epimera. Fourmanoir (1955) recorded the variety from the Comores. Consistent differences from material from New Caledonia could not be detected during our examination of numerous specimens from the western Indian Ocean. Spines on the carapace and antenna varied in number and strength, even within a small geographic range. Spination along the ventral margins of pleonal epimera 2–4 ranged from non-existent to prominent, as it does in other populations. The longitudinal ridges extending from the second transverse ridge usually carried one or two small tubercles. In some specimens from Japan a single large tubercle dominated but not in others from the same location.
De Man (1896) was the first to apply the name acanthus to specimens of Neaxius from Sulawesi, Indonesia (as Celebes) and later from New Britain, Papua New Guinea (as Nouvelle Poméranie) (De Man, 1898, 1925a). Borradaile (1900) introduced Eiconaxius taliliensis for representatives from this region but soon synonymised it with A. acanthus (Borradaile, 1903). We examined the syntypes of E. taliliensis and several specimens from nearby but could not detect consistent differences between them, nor could we detect differences from individuals from Malaysia, Palau, Philippines, Taiwan or Japan. Similarly, the syntypes of Axius acanthus mauritiana resembled others from the western Indian Ocean no more than they did those from the western Pacific. The numbers of spines on the carapace and cheliped varied over a small range between individuals and from one side of an individual to the other, as did the expression of spines, some individuals having more prominent spines than others (see figs 1–4 and especially 5). This variability was not correlated with locality.
Sakai (2011) listed Axius acanthus mauritianus, Eiconaxius taliliensis and Neaxius trondlei Ngoc-Ho, 2005 in the synonymy of N. glyptocercus. While the synonymy of Axius acanthus mauritianus and Eiconaxius taliliensis with N. acanthus is supported on morphological grounds, N. acanthus differs from N. glyptocercus in the many ways tabulated by Ngoc-Ho (2005). Neaxius trondlei from French Polynesia differs in spination from N. glyptocercus and N. acanthus for the reasons given by Ngoc-Ho (2005) (see diagnosis below).
Colour photos of live specimens indicate that the species is generally orange with stronger pigmentation on the chelipeds, anterior carapace and tailfan (Fig. 4; Anker et al., 2015: fig. 25).
description: Published as part of Poore, Gary C. B. & Dworschak, Peter C., 2018, The Indo-West Pacific species of Neaxiopsis and Neaxius (Crustacea: Axiidea: Strahlaxiidae), pp. 15-28 in Memoirs of Museum Victoria (Mem. Mus. Vic.) (Mem. Mus. Vic.) 77 on pages 17-21, DOI: 10.24199/j.mmv.2018.77.02, http://zenodo.org/record/8065257