Gymnothorax pseudomelanosomatus Loh, Shao & Chen

Loh, Kar-Hoe, Shao, Kwang-Tsao, Ho, Hsuan-Ching, Lim, Phaik-Eem & Chen, Hong-Ming, 2015, A new species of moray eel (Anguilliformes: Muraenidae) from Taiwan, with comments on related elongate unpatterned species, Zootaxa 4060 (1) : -

Gymnothorax pseudomelanosomatus Loh, Shao & Chen , new species

English name: False black body moray eel Fig. 1 , Table 1 )

Holotype: TOU-AE 5302, male, 675 mm TL, 12 September 2008, off-shore from Changbin, Taitung county, Taiwan, longline, caught by J.-S. Chiou.

Paratype: TOU-AE 5301, female, 736+ mm TL, 11 December 2008; are from Changbin, Taitung county, longline, caught by J.-S. Chiou.

Diagnosis. An elongate and unpatterned moray eel of the genus Gymnothorax with body and fins uniformly greyish brown; anus just before mid-body, preanal length 2.0 in TL; head length 11.3 in TL; depth at gill opening 27.8 in TL. Teeth uniserial, few, long and needle-like. Mean vertebral formula 7-89-206.

Description. Morphometric and meristic data are provided in Table 1 . Following values are provided for holotype, followed by paratype in parentheses. Proportions in percent of total length: preanal length 49.3 (49.7), depth at gill opening 3.6 (3.4), depth at anus 2.4 (2.3), predorsal length 6.1 (6.0), head length 8.9 (8.8). Proportions in percent of head length: length of upper jaw 43.6 (40.9), length of lower jaw 42.6 (37.9), interorbital width 13.3 (12.2), snout length 20.5 (20.6), eye diameter 8.6 (7.8).

G. prolatus G. sagmacephalus P. brummeri S. dorsalis S. sathete ...Continued on next page

G. prolatus G. sagmacephalus P. brummeri S. dorsalis S. sathete Teeth uniserial. The following values are provided for holotype, followed by paratype in parentheses. Median intermaxillary teeth 1(4); maxillary teeth uniserial about 8/8(10/10); intermaxillary teeth 6/6(6/6); vomerine teeth uniserial 5(6); dentary teeth uniserial about 14/14 (14/15) (Fig. 2). Head pores typical, three supraorbital pores, four infraorbital pores, six mandibular pores. Two to three branchial pores, branchial pores small before gill opening. Gill opening below mid-side. Total vertebrae 202–206, predorsal vertebrae 5–7, preanal vertebrae 89–89, MVF 6-89-206.

FIGURE 2. Diagrams of dentition and placement of jaw pores from the type specimens of Gymnothorax pseudomelanosomatus .sp. nov.: A, Holotype, male, TOU-AE 5302, 675 mm TL; B, paratype, female, TOU-AE 5301, 736+ mm TL.

Distribution. Known from the type series collected from southeastern Taiwan off Changbin, Taitung County at depth ca. 200 m.

Biology. A small species, maximun length 675 mm TL in male, 736 mm TL in female (gravid, distended with 1.0– 1.2 mm eggs).

Etymology. From the Greek pseudes (false) and melanosomatus , the name for the black body moray that it superficially resembles and has previously been identified as. To be treated as a noun in apposition.

Remarks. Gymnothorax pseudomelanosomatus sp. nov. can be distinguished from the similar species, G. melanosomatus Loh, Shao & Chen 2011 , by the following features ( Table 2 ): (1) grey brown body (vs. black) ( Fig 3 C); (2) longer snout length 20.5 % (vs. 17.8 %) of head length; (3) smaller eye diameter 8.2% (vs. 10.0%) of head length; (4) smaller preanal length 49.5 % (vs. 58.5 %) of total length; and (5) preanal vertebrae 89–89 (vs. 105– 109).

It also differs from G. prolatus Sasaki & Amaoka, 1991 ( Fig 3 D) by the smaller eye diameter 8.2 % (vs. 10.1 %) of head length; smaller predorsal length 6.0 % (vs. 7.2 %) of total length, and more preanal vertebrae 89 (vs. 78), and more total vertebrae 206 (vs. 179); and from G. polyspondylus Böhlke & Randall, 2000 by the longer preanal length 49.5 % (vs. 43.3 %) of total length, and in the total vertebrae 206 (vs. 233).

Figures

FIGURE 1. Gymnothorax pseudomelanosomatus sp. nov., holotype, TOU-AE 5302, 675 mm TL.

FIGURE 3. Other eight elongate unpatterned moray eels used in this study. A. Gymnothorax albimarginatus, TOU-AE 4220, 799 mm TL; B. “ G. ” dorsalis, TOU-AE 4834, 619 mm TL; C. G. melanosomatus, TOU-AE 5095, 447 mm TL; D. G. prolatus, TOU-AE 4833, 490 mm TL; E. G. phasmatodes, TOU-AE 227, 382 mm TL; F. G. sagmacephalus, TOU-AE 226, 464 mm TL; G. Pseudechidna brummeri, TOU-AE 5137, 592 mm TL; H. Strophidon sathete, TOU-AE 3028, 1261 mm TL.

Tables

TABLE 1. Morphometric and meristic data of G. pseudomelanosomatus sp. nov. and eight other unpatterned species of moray eels. Range (mean) values are provided for morphometric values and vertebral counts.

	G. pseudomelanosomatus sp. nov.	G. albimarginatus	G. melanosomatus	G. phasmatodes
TL (mm)	Holotype Paratype 675 736+	675–1060 (=6)	407–658 (n=8)	268–382 (n=6)
In % TL
Preanal length	49.3 49.7	53.3–55.2 (53.9)	56.6–59.5 (58.5)	50.4–54.5 (52.7)
Head length	8.9 8.8	10.0–12.6 (11.6)	9.3–10.5 (9.7)	9.6–10.2 (9.9)
Predorsal length	6.1 6.0	5.6–7.4 (6.7)	5.2–7.4 (6.3)	6.2–7.5 (6.8)
Depth at GO	3.6 3.4	4.8–6.7 (5.9)	2.2–3.7 (3.1)	2.7–4.2 (3.4)
Depth at anus	2.4 2.3	3.6–4.8 (4.1)	2.1–2.8 (2.4)	2.4–3.2 (2.8)
In % HL
Upper jaw	43.6 40.9	31.6–41.6 (37.6)	32.4–41.0 (35.6)	35.2–40.7 (37.6)
Lower jaw	42.6 37.9	28.4–39.3 (33.2)	31.3–37.8 (34.2)	32.6–40.4 (35.7)
Interobital width	13.3 12.2	11.2–15.2 (13.2)	9.2–14.1 (12.3)	10.9–17.3 (13.9)
Snout length	20.5 20.6	16.3–18.4 (17.5)	14.9–20.5 (17.8)	16.0–19.1 (18.0)
Eye diameter	8.6 7.8	8.4–11.0 (9.6)	8.2–11.7 (10.0)	10.8–11.5 (11.3)
Teeth
Intermaxillary	6–6 6–6	3–6	4–8	6–6
Median	1 4	0–2	0–3	0–3
Maxillary-inner	- -	-	-	-
Maxillary-outer	8–8 10–10	7–11	6–7	7–12
Vomerine	5 6	1–5	1–7	4–9
Dentary-inner	- -	-	-	-
Dentary-outer	14–14 14–15	11–15	10–12	12–17
Vertebrae
Predorsal vert.	7 5	5–6 (5)	4–7 (6)	5–6 (5)
Preanal vert.	89 89	83–90 (86)	105–109 (108)	73–79 (76)
Total vert.	206 202+	184–189 (187)	201–211 (207)	163–168 (167)