Odontodactylus japonicus (de Haan, 1844)

Brokensha, Rouane, Landschoff, Jannes & Griffiths, Charles, 2023, New and notable stomatopods (Crustacea, Stomatopoda) from Mozambique, European Journal of Taxonomy 900 (1), pp. 148-179 : 166-168

Odontodactylus japonicus (de Haan, 1844) new record

Fig. 9

Gonodactylus japonicus de Haan, 1844 : pl. 51 fig. 7 [type locality Japan].

Gonodactylus edwardsii Berthold, 1845: 48 .

Gonodactylus japonicus – de Haan 1849: 255 [text]. — Miers 1880: 116.

Odontodactylus japonicus – Alexander 1916: 10. — Holthuis 1941: 276. — Stephenson & McNeill 1955: 248–249. — Stephenson 1960: 61. — Manning 1965: 260; 1967b: 7–10, fig. 2; 1995: 20, 82. — Graham et al. 1993: 73. — Yamaguchi & Baba 1993: 176–178, fig. 9. — Ahyong & Norrington 1997: 103. — Moosa 2000: (list). — Ahyong 2001: 81–83, fig. 39. — Liu 2008: 1267 (list).

Diagnosis

Ocular scales oblique to bodyline, appressed medially. A2 scale with anterior margin smooth, without setae in adults. Rostral plate triangular, but appearing trapezoid dorsally; lateral margins sinuous; apex deflexed. Raptorial claw dactylus with 5–8 teeth on inner margin; proximal margin strongly inflated; without basal notch. AS 1–5 posterolateral angles rounded, unarmed in adults. Telson mid-dorsal surface with distinct MD carina and 4 longitudinal carinae either side of midline (double accessory MD; anterior SM; carina of inner IM denticle) in addition to carinae of primary teeth. Uropodal exopod proximal distinctly longer than distal segment; outer margin with 10–12 movable spines, distalmost evenly tapering (juveniles) to spatulate with blunt or minute spinular apex (adults).

Material examined

MOZAMBIQUE • 1 ♀ (TL 110 mm); north of Beira ; 19°49′00.0″ S, 36°05′00.0″ E; 54 m depth; 14 Jun. 1994; RV Algoa Mozambique Scad Survey; bottom trawl; SFI; SAMC – A041710 .

Colour in alcohol

Faded to creamy yellow with telson still retaining salmon colour of live specimen. Eyes green. Uropod exopod distal segment dark and proximal segment with distal third dark. Uropodal protopod, exopod proximal segment and endopod covered in dark speckles.

Colour in life

Overall colour salmon ( Ahyong 2001) or males’ bright salmon red; females’ salmon red anteriorly and blue, green posteriorly ( Manning 1967b). A2 scale salmon proximally, pink distally. Uropods yellow; exopod with outer movable spines yellow orange with blue posterior margin; endopod and distal segment of exopod with red setae.

Measurements

Female (n = 1) TL 110 mm. CI 404. A1 peduncle 0.60CL. A2 scale 0.98CL. Uropod exopod distal segment length 1.69 times proximal segment length. The largest specimen is reported from Australia at TL 175 mm ( Ahyong 2001).

Distribution and habitat

Indo-West Pacific; Australia and Japan to Western Indian Ocean from Seychelles, Madagascar, and now southern Mozambique [Sofala]. Associated with flat sandy or shelly substrata; 30–100 m depth.

Remarks

Although this is a new record for the Mozambique Channel, O. japonicus has been reported from Madagascar, not far from the locality recorded herein. The Madagascan specimen described by Manning (1967b) was collected from Ambovombe’s southern coast in shallow water at around 60 m, a similar depth to the female specimen collected from the Mozambique Channel at 54 m. The present specimen agrees in all aspects with Manning’s (1967b) diagnosis, as well as the most recent report by Ahyong (2001) of O. japonicus from Australia.

Only O. scyllarus ( Linnaeus, 1758) and O. hawaiiensis Manning, 1967 share the appressed ocular scales and the double accessory MD carinae either side of MD carina of telson with O. japonicus . Odontodactylus japonicus is distinguished from these similar species in having the longitudinal carina extending anteriorly from the inner IM denticle of the telson ( Fig. 9E ), as well as the absence of a posterolateral spine on AS 5 in adults ( Fig. 9C ). In addition, the number of teeth on the dactylus of the raptorial claw differs between the species; while O. scyllarus has two or three teeth, O. hawaiiensis and O. japonicus have more than five teeth. Odontodactylus hawaiiensis has not yet been recorded off the mainland of southern Africa.

Postlarvae settle at sizes of 19–20 mm. Along with the juveniles of O. japonicus , the postlarvae differ from adult specimens in the following characteristics diagnostic for the species: the antennal scale bears setae on its anterior margin and a posterolateral spine on AS (3)4–5, the distal movable spines on the proximal segment of the uropodal exopod are spiniform instead of spatulate and the second accessory MD carina of the telson is underdeveloped ( Manning 1967b; Ahyong 2001). Specimens above TL 60 mm are considered adult and exhibit ‘adult’ diagnostic features ( Fig. 9A–F ). No juvenile specimens were available to the present study.

Figures

Fig. 9. Odontodactylus japonicus (de Haan, 1844), ♀, TL 110 mm (SAMC–A041710). A. Anterior cephalothorax, dorsal. B. Right antennal scale, dorsal. C. AS4–5, left lateral. D. TS8 sternal keel, left lateral. E. AS6, telson and right uropod, dorsal. F. Right uropod, ventral. Scale bar: A, C, E–F = 5 mm; B = 10 mm; D = 2.5 mm.