Neotrygon kuhlii ( Müller & Henle, 1841 )

Last, Peter R., White, William T. & Séret, Bernard, 2016, Taxonomic status of maskrays of the Neotrygon kuhlii species complex (Myliobatoidei: Dasyatidae) with the description of three new species from the Indo-West Pacific, Zootaxa 4083 (4), pp. 533-561 : 535-540

Neotrygon kuhlii ( Müller & Henle, 1841)

( Figs. 1, 2 , 4 , 5a , 6a , 7a ; Table 1)

Trygon kuhlii Müller & Henle, 1841 : p. 164, pl. 50 (Vanikoro, Solomon Islands).

Lectotype. MNHN 2440 (1 of 2 specimens), female 156 mm DW, Vanikoro , Santa Cruz Group, Solomon Islands, 1829 (herein designated).

Paralectotype. MNHN 2440 (2 of 2 specimens; tail missing), female 159 mm DW, Vanikoro , Santa Cruz Group, Solomon Islands, 1829.

Other material. CSIRO H 7723-01, female 295 mm DW, Plaza fish market, Honiara, Solomon Islands, 7 May 2015.

Diagnosis. A medium-sized Neotrygon of the kuhlii -complex (reaching at least 30 cm DW) with the following combination of characters: disc broader than long, width ~1.2 times length; pectoral apices narrowly rounded; snout rather fleshy, broadly angular, angle ~107°, length 1.7–2.1 times interorbital width; maximum width relatively well back on disc, length from snout tip to pectoral-fin insertion 1.8–1.9 times and disc width 2.5–2.6 times horizontal distance from snout tip to maximum disc width; preoral length 2.4–2.8 times mouth width; internasal distance 1.5–1.8 in prenasal length; interspiracular distance 13–15% DW; nostril length 2.8–4.1% DW; nasal curtain width 8–8.3% DW; small mouth, width 6.4–6.8% DW; horizontal distance from cloaca to caudal sting base ~55% of disc length; thornlets present in nuchal region, absent from tail in all sizes; dermal denticles absent; pectoral-fin radials 113 (based on new specimen); total vertebral centra (including synarcual) 133, trunk centra (including synarcual) 39; blue spots very small and sparse, largest spot on disc 0.3–0.5 times eye width; 0–6 (mean 3.0) blue spots on medial belt, largest ~2.1% DW; mask-like marking pronounced, not covered with dark peppery spots; ventral surface of disc and pelvic fins with broad dark greyish submarginal bands; ventral tail fold and adjacent tail bluish grey when fresh.

Distribution. Tropical South-West Pacific, off the Solomon Islands; Santa Cruz Islands and Guadalcanal. Probably more widespread in Oceania but limits of its distribution need to be defined.

Remarks. The two former syntypes (MNHN 2440, 156 and 159 mm DW) from the eastern Solomon Islands (Vanikoro) are both females, presumably immature. The designated lectotype (156 mm DW) has strongly faded skin, almost pale brown with evidence of very small, white ocelli on both (confined to two spots on right side), with the tail intact; white central core of ocellus 1.2–1.7 mm diameter, surrounded by thin darker ring ~ 0.5 mm; the tail is mainly pale with two dark saddles confined to the dorsal part after caudal sting; entire tail tip is brownish on both surfaces. The designated paralectotype (159 mm DW) has ~29 similar-sized ocelli (some possibly missing), still evident beside orbits and irregularly dispersed over disc (diameter white core 1–2.6 mm); additional dark speckles are present on the orbital membrane, interorbit and over the central disc (<1.5 mm diameter). In both specimens, the posterior margins of ventral disc are probably darker than centrally; outer edge of ventral fold darker than its base (discussed by Müller & Henle, 1841).

A third much smaller syntype (MNHN A7931) collected from New Guinea by Quoy & Gaimard, is a late-term male embryo (~ 100 mm DW) with a rudiment of its umbilical cord still evident. The specimen is heavily bleached, being uniformly pale with no indication of colour ( Fig. 3a ). Morphometrics of these preserved types may be slightly affected by preservation, as the lectotype in particular has very flexible skin that may alter some anterior measurements. The fourth syntype from Leiden is probably RMNH 2472, an adult male (~ 270 mm DW) which is dried and stuffed ( Fig. 3b ).

Identification of the primary type specimen used in the Müller & Henle’s description and excellent figure to designate a lectotype of the species has proven problematic. The number of blue spots and the presence of two caudal stings in their figure does not coincide with any of the types. Also, the illustration is of a female whereas the probable Leiden syntype is an adult male. Either their illustration is a composite image (most likely) or the dry Leiden adult male is not a syntype. The Leiden type (RMNH 2472) is listed as from Java, collected by Kuhl & van Hasselt. Müller & Henle’s description, the type location is listed as ‘Indien’ which although often presumed to be India, was often used for East India or East Indies, present day Indonesia. Thus, this provides some support for the Javan specimen as the fourth syntype of T. kuhlii . But it should be noted that in other species descriptions, Müller & Henle refer to Java in the locations provided so there is still an element of uncertainty over the exact syntype specimen. Müller & Henle’s description also refers to a sting (rather than two): ‘der Stachel am Ende des vordem Viertels’. Still, a discrepancy remains as to their sizes; the syntype measured appears to be about 139.5 mm DW (largest width '5 Zoll, 4 Linie' based on Müller & Henle) which is much smaller than the first size of maturity of any member of the kuhlii -complex. The paucity and very small sizes of blue spots appears typical of maskrays from the Solomon Islands; blue-spotted maskray populations from India (inferentially specified as the location of the fourth syntype by Eschmeyer, 2016) and Indonesia (often referred to as ‘Indien’ in old museum labels and incorrectly accorded to India) have medium to large blue spots, usually in much higher densities. The size of spots and their distribution in Müller & Henle’s figure ( Fig. 1) is very similar to that of the two Vanikoro types ( Fig. 2 ). On that basis, the most complete MNHN specimen, a 156 mm DW female in good condition with tail and caudal sting intact, is hereby designated as the lectotype. The second Vanikoro type becomes a paralectotype. This embryonic syntype (MNHN A7931) probably equals N. australiae sp. nov., and the dried RMNH syntype probably equals N. caeruleopunctata sp. nov. based on its size and capture location.

The meristic details of the N. kuhlii types were not obtained so counts are based solely on a newly collected specimen ( CSIRO H 7723-01): total pectoral-fin radials 113; propterygium 45, mesopterygium 19, metapterygium 49. Pelvic-fin radials: 1 + 25–26. Vertebral centra total (including synarcual) 133; total (excluding synarcual) 128; monospondylous (including synarcual) 44; monospondylous (excluding synarcual) 39; pre-sting diplospondylous 64; post-sting diplospondylous 25. Count of the pectoral-fin radials (i.e. 113) is high for a kuhlii -group member. This specimen resembles the Vanikoro lectotype in shape and colour. Its COI sequence indicates that this species is distinct from all other kuhlii -group members (Appendix 1). In a similar analysis for the chondrichthyan Tree of Life project using the NADH2 gene, the specimen was basal and separate from all other forms of the kuhlii -group (G. Naylor, pers. comm.).

N. kuhlii N. australiae sp. nov.

Lectotype Paralect. Other Holotype Paratypes

material Min. Max. Mean

Disc width (mm) 156 159 295 213 171 343

Total length 189.2 – 211.2 224.6 159.1 223.5 199.5 Disc length 82.2 81.3 81.7 82.6 79.8 85.1 82.4 Snout to pectoral-fin insertion 71.4 70.0 71.9 72.0 68.1 74.9 71.7 Disc thickness 12.0 12.3 11.1 12.6 11.8 14.3 12.8 Snout (preorbital) length 17.2 16.4 16.1 14.1 13.3 14.6 13.8 Snout (preorbital) horizontal length 14.4 13.6 13.6 12.0 10.5 11.3 11.0 Pelvic-fin (embedded) length 17.3 17.0 19.9 19.3 18.4 22.3 21.0 Width across pelvic-fin base 14.5 13.8 16.4 15.4 15.6 18.4 16.7 Greatest width across pelvic fins 31.7 34.0 39.7 41.2 29.6 40.1 35.1 Cloaca origin to tail tip 120.2 – 141.1 154.1 90.2 153.7 129.9 Tail width at axil of pelvic fins 7.2 7.4 7.6 8.3 7.3 9.0 8.1 ......continued on the next page N. kuhlii N. australiae sp. nov. Lectotype Paralect. Other Holotype Paratypes material Min. Max. Mean

Figures

FIGURE 2. Dorsal view of Neotrygon kuhlii types from Vanikoro, Solomon Islands (preserved): (A) lectotype (MNHN A 2440, 1 of 2, female 154 mm DW); (B) paralectotype (MNHN A 2440, 1 of 2, female 162.7 mm DW).

FIGURE 3. Dorsal view of: (A) embryonic syntype of Neotrygon kuhlii from West Papua, New Guinea (MNHN A 7931, embryo 99.7 mm DW; probably equals Neotrygon australiae); (B) dried probable syntype of Neotrygon kuhlii from Java, Indonesia (RMNH 2472, adult male ~ 271 mm DW; probably equals Neotrygon caeruleopunctata).

FIGURE 4. Freshly caught specimen of Neotrygon kuhlii (CSIRO 7723 - 01, female 295 mm DW) from Honiara, Solomon Islands: (A) dorsal view; (B) ventral view.

FIGURE 5. Oronasal region of: (A) Neotrygon kuhlii (CSIRO 7723 - 01, female 295 mm DW); (B) Neotrygon australiae sp. nov. (CSIRO CA 3247, adult male 379 mm DW); (C) Neotrygon caeruleopunctata sp. nov. (CSIRO H 6202 - 03, adult male 311 mm DW); (D) Neotrygon orientale sp. nov. (CSIRO H 6130 - 01, female 254 mm DW).

FIGURE 6. Lateral view of the post-caudal sting tail of: (A) Neotrygon kuhlii (CSIRO 7723 - 01, female 295 mm DW); (B) Neotrygon australiae sp. nov. (CSIRO CA 4307, female 306 mm DW); (C) Neotrygon caeruleopunctata sp. nov. (CSIRO H 6202 - 04, female 324 mm DW); (D) Neotrygon orientale sp. nov. (CSIRO H 7848 - 01, female 343 mm DW).

FIGURE 7. Lateral view of the mid-tail showing respective heights of the dorsal and ventral tail folds: (A) Neotrygon kuhlii (CSIRO 7723 - 01, female 295 mm DW); (B) Neotrygon australiae sp. nov. (CSIRO CA 4307, female 306 mm DW); (C) Neotrygon caeruleopunctata sp. nov. (CSIRO H 6202 - 04, female 324 mm DW); (D) Neotrygon orientale sp. nov. (CSIRO H 7848 - 01, female 343 mm DW).