Oratosquillina nordica Ahyong & Chan, 2008, sp. nov.

Oratosquillina nordica sp. nov.

(Figs. 1, 2)

Squilla quinquedentata.— Tweedie 1934: 36 [Singapore]. — Chuang 1961: 181: pl. 82 [Peninsular Malaysia] [not S. quinquedentata Brooks, 1886].

Oratosquilla quinquedentata.— Dingle et al. 1977: 8, 10 [Phuket, Thailand]. — Manning 1978: 23 [part, Gulf of Thailand specimen]. — Naiyanetr 1980: 43 [Thailand] [not O. quinquedentata (Brooks, 1886)].

Oratosquillina quinquedentata.— Sun et al. 1997: 26, fig. 11 [Guangxi and Guangdong provinces, China]. — Wang & Liu 1998: 138 [South China Sea]. — Naiyanetr 1998: 128 [Andaman Sea and Gulf of Thailand]. — Liu & Wang 1999: 579 [China and Taiwan]. — Moosa 2000: 411, 449. — Ahyong & Moosa 2004: 64 –65 [Anambas Islands, southern South China Sea, Indonesia] [not O. quinquedentata (Brooks, 1886)].

Type material.— HOLOTYPE: NTOU S- 00028, male (TL 98 mm), fishing port at Nanfang-ao, Yilan County, Taiwan, 5 Oct. 1995. PARATYPES: Taiwan, Yilan County, fishing port at Dasi: NTOU S- 00029, 2 females (TL 94–105 mm), 3 Aug. 1996; NTOU S- 00030, 3 males (TL 100–118 mm), 1 female (TL 124 mm), 4 Aug. 1996; NTOU S- 00031, 1 male (TL 56 mm), 12 Dec. 1995; NTOU S- 00032, 9 males (TL 44–118 mm), 5 females (TL 52–98 mm), 24 Sep. 1996; NTOU S- 00033, 2 males (TL 48–59 mm), 3 females (TL 47–49 mm), 3 Dec. 1996; NTOU S- 00034, 1 female (TL 75 mm), 8 Jan. 2008; NTOU S- 00035, 1 female (TL 96 mm), 7 Mar. 2008; TMCS-0065, 1 female (TL 68 mm), J. T. Lin, 28 Feb. 1989; NIWA 44723, 1 female (TL 100 mm), trawled, coll. S. Ahyong et al., 25 May 1998; NIWA 44724, 1 male (TL 85 mm), 3 females (TL 71– 80 mm), coll. S. Ahyong et al., 7 Mar. 2008.

Other material examined.— Thailand, Andaman Sea: ZRC 1999.2087, 1 male (TL 104 mm), 2 females (TL 95–114 mm), coll. P. Ng, 24 Aug. 1999; PMBC 16111, 1 male (TL 82 mm), 7°45’N, 97°58’E, 70 m, BIO- SHELF H38, 9 May 1996; PMBC 16112, 3 females (TL 98–124 mm), Phuket, fishing port, coll. P. Ng & P. Davie, Dec. 1998; QM W25567, 1 male (TL 113 mm), Phuket, fishing port, coll. P. Ng & P. Davie, Dec. 1998; AM P58288, 1 male (TL 128 mm), Pichai, Phuket, fishing port, coll. P. Ng, Dec. 1999.

Thailand, Gulf of Thailand: ZRC 1998.1161, 1 male (TL 95 mm), 1 female (TL 128 mm), Ang Sila fishing port, Chonburi Province, coll. P. Ng, 29 Sep. 1998; ZRC 1999.2186, 1 male (TL 120 mm), Sirachai, Ko Sichang seaport, coll. S. Ahyong et al., 12 Nov. 1999.

Peninsular Malaysia: ZRC 1999.2146, 1 male (TL 98 mm), Tanjung Datu, 02°60.00’N, 109°40.75’E, 32.9 m, trawled, RV ‘Manihine’, 24 Nov. 1955.

Singapore: ZRC 1970.10.21.68–70, 1 male (TL 57 mm), 2 females (TL 78–91 mm), Siglap, Singapore, coll. M. Tweedie Jul. 1934; ZRC 11970.10.21.66–67, 2 females (TL 67–100 mm), Siglap, Singapore, coll. M. Tweedie, Jun. 1934; ZRC 1990.15–16, 1 male (TL 128 mm), 1 female (TL 131 mm), Singapore, fish market, probably from South China Sea, coll. P. Ng, 18 May 1989.

Indonesia: Anambas Islands: ZRC 2003.0511, 1 male (TL 112 mm), E coast of Jemaja I., mouth of Jebung Bay, 02°53.03–55.39’N, 105°50.55–51.15’E, 24–31 m, trawl, stn. EA TT04, coll. T. Tan et al., 13 Mar. 2002.

Southern South China Sea: ZRC 1988.2278, 1 male (TL 127 mm), bottle B, no. 5, 17:30, 20 Apr. 1972; ZRC 1988.2279, 1 male (TL 101 mm), May 1972; ZRC 1999.2171, 1 female (TL 120 mm), 26 Nov. 1982; ZRC 1999.2171, 1 male (TL 125 mm), 2 females (TL 108–117 mm), 15 Dec. 1982.

Taiwan: NTOU, 2 males (TL 44–57 mm), 1 female (TL 49 mm), Magong, Penghu County, fish market, 16 Sep. 1996; TMCS-0043, 1 male (TL 85 mm), 1 female (TL 106 mm), Penghu County, coll. J. T. Lin, 23 Apr. 1986; TMCS-0074, 1 male (TL 70 mm), 1 female (TL 58 mm), Taiwan, no specific locality; NTOU, 1 male (TL 71 mm), Taiwan, no specific locality.

Diagnosis. — Raptorial claw dactylus with 5 teeth. Mandibular palp present. TS5 with posterior lobe of lateral process with blunt apex. TS6 with anterior lobe of lateral process slender, digitiform, about twice as long as wide. AS 1–3 lateral carinae posteriorly unarmed. Telson dorsolateral surface without supplementary dorsolateral carinae.

Description.— Dorsal integument pitted.

Eye extending beyond midlength but not apex of A1 peduncle segment 1; cornea strongly bilobed, set slightly obliquely on stalk; CI 400–530. Ophthalmic somite anterior margin rounded. Ocular scales truncate, separate.

A1 peduncle length 0.86–0.97CL. A1 somite dorsal processes trianguloid, directed anterolaterally, apices blunt. A2 scale length 0.52–0.58CL.

Rostral plate squarish, slightly broad than long; lateral margins carinate; apex truncate. Carapace anterior width 0.48–0.53CL; anterolateral spines not extending beyond base of rostral plate; branches of anterior bifurcation of median carina indicated only anteriorly by faint, short swellings; posterior median projection obtuse.

Raptorial claw dactylus with 5 teeth; outer margin gently sinuous; outer proximal margin obtuse. Propodus distal margin unarmed. Carpus dorsal carina undivided. Merus outer inferodistal spine stout.

Mandibular palp 3-segmented. Maxillipeds 1–4 with epipod. Maxilliped 5 basal segment with small, ventrally directed tooth.

Pereopod 1–3 basal segments unarmed; endopod segments fused.

TS6–8 with slightly divergent submedian carinae. TS5 lateral process anterior lobe spiniform, recurved anterolaterally; posterior lobe short with blunt apex. TS6 lateral process anterior slender, digitiform, width about half length, less than one-third width of posterior lobe; posterior lobe large, triangular. TS7 lateral process anterior lobe triangular, much smaller than triangular posterior lobe. TS8 lateral process triangular, apex acute; sternal keel obtusely angular to rounded.

Male pleopod 1 endopod with petasma; posterior “endite” present; tube process curved, distinctly longer than hook process; hook process without apical spine.

AS 1–5 with submedian carinae slightly divergent posteriorly. AS 6 with small ventrolateral spine anterior to uropodal articulation; sternum posterior margin unarmed. Abdominal carinae spined as follows: submedian 5–6, intermediate 4–6, lateral 4–6, marginal 1–5.

Telson as long as broad; apices of intermediate teeth extending posteriorly to base of submedian teeth; prelateral lobe longer than margin of lateral tooth. Submedian, intermediate and lateral primary teeth each with smooth carina, that of lateral tooth extending anteriorly to distal third of prelateral lobe. Marginal denticles rounded, submedians and intermediate with low dorsal tubercle or swelling; denticle formula: submedian 2 or 3, intermediate 6–9, lateral 1. Median carina interrupted proximally, posterior spine slender, overhanging rounded tubercle. Dorsolateral surface with rows shallow pits; supplementary longitudinal carinae absent. Telson ventral surface with long postanal carina, extending posteriorly to or almost to midpoint between anal pore and posterior margin; ventrolateral carina extending to base of intermediate tooth.

Uropodal protopod terminating in 2 slender spines; lobe on outer margin of inner spine narrower than to as broad as adjacent spine, proximal margin concave; with small tooth proximal to endopodal articulation.

Uropodal exopod proximal segment with 7 or 8 movable spines on outer margin, distalmost not reaching midlength of distal segment; distal margin with 2 ventral spines, outermost longer. Exopod distal segment slightly longer than proximal segment.

Colour in life.— Light gray-brown dorsally, darker mid-dorsally. Carinae and grooves of carapace, submedian carinae and posterior margins of body somites red. Telson with median carina and carinae of primary teeth red; median carina with narrow dark band across anterior and posterior third. Uropodal protopod with red terminal spines; endopod black on distal half; exopod with pink movable spines; exopod distal segment yellow with inner half black.

Etymology.— Derived from the French, Nordiques, northern, alluding to the northern hemisphere distribution of the new species in comparison to the southern hemisphere distribution of O. quinquedentata.

Measurements.— Male (n = 32) TL 44–128 mm, female (n = 34) TL 45–131 mm. Other measurements of the holotype: CL 21.3 mm, anterior carapace width 10.8 mm, cornea width 4.6 mm, A1 peduncle length 18.7 mm, A2 scale length 12.4 mm.

Habitat.— Burrows in sandy-mud or muddy substrates, including mud-flats; shore to 70 m depth.

Remarks.— Oratosquillina nordica sp. nov. has previously been confused with Oratosquillina quinquedentata (Brooks, 1886) (type locality: the Arafura Sea, 09°59’S, 139°42’E). The two species are nearly identical morphologically, being distinguished by the width of the anterior lobe of the TS6 lateral process. The anterior lobe of the TS6 lateral process in O. quinquedentata is broad and trapezoid, about as long as wide, with its width almost one-half that of the posterior lobe. The TS6 anterior lobe in O. nordica, however, is much more slender, digitiform, with its width about half its length, and between one-quarter and one-third the width of the posterior lobe. Oratosquillina nordica also differs from O. quinquedentata in usually having a triangular rather than rounded TS7 anterior lateral lobe, though variability of this feature in O. nordica limits its taxonomic value. Juveniles and some adults of O. nordica also have a rounded anterior lateral lobe of TS7.

In the slender TS6 anterior lobe, O. nordica resembles O. pentadactyla (Manning, 1978) (Indonesia and southern India), which has also been confused with O. quinquedentata (see Kemp 1913; Holthuis 1941). Oratosquillina nordica and O. quinquedentata both differ from O. pentadactyla in having a blunt instead of sharp posterior lobe on the TS5 lateral process, a squarish instead of rectangular rostral plate and unarmed lateral carinae on AS 1–2.

Oratosquillina nordica is generally morphologically uniform, with allometric variation in the width of the TS6 anterior lateral lobe (slightly wider in juveniles than in adults), the shape of the anterior lobe of the TS7 lateral process as already noted, and in the width of the lobe on the outer margin of the inner spine of the uropodal protopod. In O. nordica, the lobe is proportionally narrower than the adjacent spine in specimens down to about 60 mm TL, below which the lobe is as wide as the adjacent spine. The modified pleopod 1 endopod of males is fully developed in specimens of 59 mm TL or larger.

Oratosquillina quinquedentata sensu stricto is presently known only from the southern hemisphere from a region bounded by northern Australia, southern Indonesia and Papua New Guinea (Western Australia to Queensland and the Kai Islands, Indonesia) (Ahyong 2002) (Fig. 2). As shown by Manning (1978), records of O. quinquedentata from western Indonesia (Holthuis 1941) are based on O. pentadactyla. The known ranges of O. nordica and O. quinquendentata are apparently discrete, for neither are known from central Indonesia. Oratosquillina nordica ranges from the Andaman Sea to the southern South China Sea including Singapore and Malaysia, and northwards to the Gulf of Thailand, China and Taiwan (Fig. 2). Records of O. quinquedentata from India and Sri Lanka (Kemp 1913; Odhner 1923; Manning 1978; Ghosh 1990) require confirmation. Manning’s (1978: fig. 12) figure of a specimen from Bombay resembles O. quinquedentata sensu stricto in the shape of the lateral processes of TS6, but differs in having noticeably smaller eyes; it may represent a third species.

The species of Oratosquillina can be distinguished in the key below. Note that O. megalops (Manning, 1980) is excluded from the key in anticipation of its synonymy with O. inornata (Tate, 1883) (Ahyong, Chan & Liao, unpublished).

Distribution.— Andaman Sea, Gulf of Thailand, Peninsular Malaysia, Singapore, Indonesia (Anambas I.), China (Guangxi and Guangdong provinces), and Taiwan.