Gobiodon irregularis, Herler, Juergen, Bogorodsky, Sergey V. & Suzuki, Toshiyuki, 2013

Herler, Juergen, Bogorodsky, Sergey V. & Suzuki, Toshiyuki, 2013, Four new species of coral gobies (Teleostei: Gobiidae: Gobiodon), with comments on their relationships within the genus, Zootaxa 3709 (4), pp. 301-329 : 309-313

Gobiodon irregularis , sp. nov.

Rufous Coralgoby

Figs. 3 , 4 , 10 & 11 ; Tables 1 , 4 , 5 & 10

Gobiodon sp. 1 Herler and Hilgers 2005 (part): 120, Figs. 13a, b; Herler et al. (2009): 733, Fig. 4 .

Holotype. NMW 95078, 30.1 mm SL, Gulf of Aqaba, Egypt, Dahab, “Islands” (28°28’38.50” N, 34°30’47.10” E), 11 m, coll. J. Herler, 13 November 2005.

Paratypes. Four specimens: NMW 95565, 23.4 mm SL, Gulf of Aqaba, Egypt, Dahab, “Napoleon Reef” (28°28’14.4” N, 34°30’31.4” E), 1 m, coll. J. Herler, 18 November 2005. NMW 95566 ( CH 232-41-019 in Herler & Hilgers, 2005), 16.1 mm SL, 3 m, 4 May 2004, other data same as holotype. MNHN 2006–1699, 32.3 mm SL, 5 m, 19 November 2005, other data same as holotype. BMNH 2006.10.6.1, 29.6 mm, 3 m, 17 November 2005, other data same as holotype.

Additional material. Gobiodon irregularis : CH 232-41b-057, 22.3 mm SL, Egypt, Dahab, coll J. Herler, 13 May 2012; CH 232-41-020, 31.2 mm SL, Egypt, Dahab, coll J. Herler, 0 4 May 2004; SMF, uncatalogued, 27.6 mm SL, Saudi Arabia, Farasan Archipelago, coll. S.V. Bogorodsky, 27 February 2012; PMR VP 3201, 23.5 mm SL, Egypt, Sharm el Sheikh, Sharm el Moya, coll. S.V. Bogorodsky, 30 June 2011. Gobiodon RW sp. 1 (identified as G. irregularis ): SAIAB 70430, juvenile, 15 mm SL, Indian Ocean, Rodrigues, coll. P. Heemstra, 22 October 2001.

Comparative material. Gobiodon cf. fulvus (sensu Winterbottom & Emery 1986) : uncatalogued ( DNA sample), 23.9 mm SL, Maldives, Makunudu, coll. J. Herler, 17 March 2007; uncatalogued ( DNA sample), 23.7 mm SL, southern Taiwan, Kenting, coll. J. Herler, 0 6 December 2008; OMNH P40259 ( Fig. 9 F), 20.8 mm SL, Japan, Ryukyu Islands, Iriomote Island, coll. T. Suzuki and M. Suzuki, 22 August 2004. Gobiodon oculolineatus Wu 1972 : OMNH P40260 ( Fig. 9 G), 22.6 mm SL, Japan, Ryukyu Islands, Okinawa Island, coll. T. Suzuki and M. Suzuki, 0 4 May 1996.

Diagnosis. Dorsal-fin rays VI + I,10-11 (usually 11); anal-fin rays I,9-10 (usually 9); head and body naked; body relatively elongate (depth 35.1–39% SL) and compressed; head slightly pointed in juveniles, becoming more rounded in adults; snout sometimes with a slight hump above upper lip; no groove between isthmus and interopercle; caudal peduncle slender (depth 14.5–15.8% SL); caudal fin relatively long (22.6–24.6% SL). Juveniles and subadults greenish or brownish green with up to seven red bars with bluish interspaces on head and pectoral-fin base, three anteriormost bars also run across eye; nape and dorsal part of body with irregular red lines and small spots; lines and dots usually vanish in adults of more than 3 cm TL; body becomes uniformly brown or reddish brown, usually with remnants of the orbital and suborbital bars.

Description (based on 5 types and several non-type specimens (for osteology)). Head and body compressed. Head relatively deep, posterior part of body slender, caudal peduncle low. Body proportions and meristics for types are provided in Tables 4 and 5 , respectively. Dorsal-fin rays VI + I,10– 11 (10:1, 11:4); anal-fin rays I, 9 –10 (9:4, 10:1); pectoral-fin rays 20 (n = 5); pelvic-fin rays I,5 (all specimens); caudal fin with 15–17 segmented and branched rays; disc short (not reaching anus) and cup-shaped with significant frenum between spines. First dorsal fin as high as D 2 in juveniles and somewhat triangular, but lower than D 2 in adults. No scales. Gill opening less wide than pectoral-fin base, ending ventrally in opposite of 3rd or 4th lower pectoral-fin ray. Gill rakers 0–3 + 7–8. No groove between interopercle and isthmus. Mouth terminal, relatively straight. Upper jaw reaching to about below anterior margin of orbit or to mid-orbit. Upper lip slightly curved. One outer row of up to 10 larger, slightly recurved teeth in upper and lower jaw, and increasing in size towards symphysis. Several rows of small, slender and recurved teeth in both jaws behind the outer row. Lower jaw with a pair of large, postsymphysial canines on each side, one often much smaller or absent, probably due to tooth loss and replacement. Anterior and posterior nasal openings at the end of short tubes. Head sensory canals typical for Gobiodon ( Winterbottom & Harold 2005) , with anterior oculoscapular (pores NA (paired), AI, PI (unpaired), SO, AO and IT (paired)) and preopercular (three pores on each side) canals present.

Life colouration. Juveniles greenish with seven broad red bars on head and pectoral-fin base ( Fig. 3 B): first from orbit to upper lip, second and third through orbit and across cheek, fourth to sixth, wider and somewhat wavy, across opercle, seventh wide across pectoral-fin base; interspaces bluish or greyish; red bars become irregular and wavy on postorbital area; nape and dorsal half of body with red vermiculations; both dorsal fins sometimes with narrow bright bluish band along the base; banded pattern of internal pigment along vertebral column; median fins greenish. Subadults brownish green or brown with small red spots and irregular short lines on nape and dorsal part of body; only the three more distinct red suborbital head bars remain visible ( Fig. 4 B–E). Adults uniformly reddish brown or brown, including fins ( Figs. 3 A, 4A), nape and upper half of body covered with dark-brown dots; remnants of orbital bars, extending onto suborbital area, may be visible.

Preserved colouration. Specimens uniformly light or dark brown. Bars and dots in juveniles and subadults may be retained. Bars through eyes not visible.

Molecular genetics. The present analysis includes the sequences of the specimen with the original number G. sp. 1_GA1 ( Herler et al. 2009) from the Gulf of Aqaba, Red Sea as well as of one of the paratypes (NMW 95565). See Table 1 for Genbank accession numbers. The genetically closest species to G. irregularis sp. nov. is G. oculolineatus Wu, 1972 ( Duchene et al. 2013) . The p -distance based on 12S and 16S rRNA comparisons between these two species is 0.013 (1.3% genetic difference; Herler, unpublished data).

Habitat. Gobiodon irregularis displays a generalised habitat selection and occupies a great range of Acropora corals. It occurs in deeper water regions (lower reef slope and fore reef areas) and is most common in corals such as Acropora samoensis , A. valida and A. secale but was also observed in A. eurystoma and A. pharaonis in the northern Red Sea.

Distribution. This species was found in the Gulf of Aqaba, northern Red Sea main basin (near Marsa Alam, Egypt and Al Wajh, Saudi Arabia) and in the southern Red Sea (Dahlak Archipelago, Eritrea; Farasan Archipelago, Saudi Arabia). It is also known from Rodrigues in the western Indian Ocean (identified as Gobiodon RW sp. 1 by Richard Winterbottom from a photo by Phil Heemstra; Fig. 4 F).

Etymology. This species is named “ irregularis ” for its variable colouration, in particular its irregular red wavy lines on the head and upper body in juveniles and subadults. Suggested common name: Rufous Coralgoby (colored red-brown when adult).

Remarks. The confusion of this species with G. bilineatus and grouping with Gobiodon sp. 1 ( Herler & Hilgers 2005) was mainly caused by the very similar adult colouration, although the body shape (in particular the rounder head and deeper caudal peduncle in G. bilineatus ) and lines on the head are different in adult fishes. Also, D2, A and P fin-ray counts are on average higher in G. irregularis , but the overlapping range of values does not permit definite identification. As confirmed by mitochondrial DNA investigations, the two species are genetically very distinct; the same holds true for the juvenile and subadult colouration of both. Although body shape differences are recognizable, geometric morphometric analysis failed to reveal statistically significant shape differences between the two species (MANOVA on the first 5 principal components: p = 0.08), but this may merely reflect the very low sample number, especially of G. bilineatus . Discrimination between G. irregularis and G. bilineatus can possibly be based on life colouration, at least among Red Sea specimens. Juveniles and subadults may be distinguished by the five thin blue lines on the head and the uniformly coloured body in G. bilineatus , versus the broader irregular red bars with bluish/greyish interspaces below the eye and the irregular lines and dots on the body of G. irregularis . In adults, lines on the head or bars may vanish in both species, but there are always two bright bluish lines running across the eye in G. bilineatus , which are far less distinct in G. irregularis . Moreover, body colouration is bright orange to orange-red in G. bilineatus and rather brownish to red-brown in G. irregularis , but this varies: the Indian Ocean/western Pacific populations, which are genetically very close to Red Sea G. bilineatus ( Fig. 11 ), have a darker body ( Fig. 9 A, B). Genetically, the closest relative of G. irregularis is G. oculolineatus ( Duchene et al. 2013) . In fact, the two species have a genetic distance of <2%, which suggests intrarather than interspecific variation. However, their colour pattern is distinct, in that G. oculolineatus has only two bars across the eye and suborbital area, similar to the first two in G. irregularis , but with a wide, conspicuously coloured (dark red to brown) interspace. In addition, G. oculolineatus has no lines on the body, not even as juveniles. Therefore, we consider the two species as distinct, similar to other closely related species pairs, such as G. sp. D sensu Munday et al. (1999) and G. quinquestrigatus (P. Munday, personal communication). Gobiodon irregularis is also a close relative of G. reticulatus Playfair 1867 ( Fig. 11 ). Similarities with the latter exist in finray counts but also in the head colour pattern of subadult G. irregularis . The two species can be discriminated not only genetically but also based on life colouration in the field: G. reticulatus has large spots on the body and 5 or 6 rather regular and broad bluish head bars, whereas the small spots in juvenile and subadult G. irregularis are restricted to the upper half of the body and adults have only two less distinct orbital bars. They also differ in their habitat requirements in that G. reticulatus usually lives in deep water (up to 30 m) and only occupies a few, particular Acropora species which are rarely used by other species (see Herler & Hilgers (2005) and Dirnwoeber & Herler (2007)). Another species with bright lines on the head as in G. bilineatus , G. irregularis and G. oculolineatus is G. fulvus sensu Winterbottom & Emery (1986) . This species, however, is rarely referred to in the literature and the name G. fulvus seems commonly applied to a species which does not agree with Herre’s (1927) original description (he mentioned a black opercular spot, no headlines and a pale orange body, all of which contradict the species recorded by Winterbottom and Emery (1986) and the specimens from the Maldives, Japan and Taiwan examined herein). However, G. fulvus sensu Winterbottom & Emery (1986) can be distinguished from the three species mentioned above by a very dark body, two distinct bright blue lines with black borders across the eye that extend obliquely to the posterior edge of the preopercle, and distinct white bands along the D2 and A base (also with black borders). The fin-base bands may be hardly visible in life (JH, personal observation) and therefore this species may be most easily mistaken in the field with the species mentioned above.

Figures

FIGURE 3. Gobiodon irregularis sp. nov. A. freshly collected adult, holotype, NMW 95078, 30.1 mm SL, Dahab, Egypt, Red Sea. B. freshly collected subadult, CH 232 - 41 b- 057, 22.3 mm SL, Dahab, Egypt, Red Sea. Photos by J. Herler.

FIGURE 4. Gobiodon irregularis sp. nov. A. freshly collected adult, paratype MNHN 2006 - 1699, 32.3 mm SL, Dahab, Egypt, Red Sea; B. freshly collected adult, CH 232 - 41 - 020, 31.2 mm SL, Dahab, Egypt, Red Sea; C. freshly collected adult, SMF uncatalogued, 27.6 mm SL, Farasan Archipelago, Red Sea; D. freshly collected subadult, paratype NMW 95565, 23.4 mm SL, Dahab, Egypt, Red Sea; E. alive subadult, PMR VP 3201, 23.5 mm SL, Sharm el Moya, Egypt, Red Sea; F. freshly collected juvenile, SAIAB 70430, 15 mm SL, Rodrigues, western Indian Ocean. Photos by J. Herler (A, B, D), S. V. Bogorodsky (C, E), P. Heemstra, © SAIAB (F).

FIGURE 9. Comparative material. Freshly collected adults: Gobiodon cf. bilineatus sp. nov. A. uncatalogued, 28.9 mm SL, Kagi Island, Maldives. B. uncatalogued, 22.9 mm SL, Kenting, southern Taiwan. C. Gobiodon prolixus, ROM 73338, holotype, male 26.2 mm SL, Nha Trang, Vietnam. D. Gobiodon sp. D sensu Munday et al. (1999), uncatalogued, 29.9 mm SL, Hembadhu Island, Maldives E. Gobiodon quinquestrigatus, uncatalogued, 28.7 mm SL, Kenting, southern Taiwan; F. Gobiodon cf. fulvus (sensu Winterbottom & Emery 1986), OMNH P 40259, 20.8 mm SL, Iriomote Island, Japan. G. Gobiodon oculolineatus, OMNH P 40260, 22.6 mm SL, Okinawa Island, Japan. H. Gobiodon ceramensis, OMNH P 34042, 35 mm SL, Ryukyu Island, Japan. Gobiodon unicolor, preserved holotype, MNHN A- 4015, 31 mm SL, I. entire specimen. J. close-up of black opercular spot (arrow) on the right side. Photos by J. Herler (A, B, D, E, I, J), R. Winterbottom (C), T. Suzuki (F-H).

FIGURE 10. First two principal components of a PCA of Procrustes coordinates of 15 landmarks and 6 semi-landmarks put on 111 specimens of Gobiodon. The holotype (MNHN A- 4015) of G. unicolor (Castelnau, 1873) is marked by a red circle. RS = Red Sea. For species abbreviations see Table 1.

FIGURE 11. Neighbor-joining tree of 23 taxa of Gobiodon and 2 Paragobiodon species (as nearest neighbour at genus level) based on combined sequences of partial 12 S and 16 S rRNA mitochondrial genes. According to a model test in MEGA 5.05, a K 2 P-model with a gamma-parameter of 0.23 and pairwise deletions of gaps / missing data were selected. Numbers at nodes are bootstrap values (1000 replicates); values <50 are not shown. Bar below tree shows substitutions per site. The 4 new species are marked with a box. For abbreviations of species and localities see Table 1. Undescribed species are given with references in parentheses: JH = according to Herler et al. (2009), PM = according to Munday et al. (1999).

Tables

TABLE 4. Body proportions of holotype and three adult paratypes of Gobiodon irregularis sp. nov. from the northern Red Sea. The juvenile paratype NMW 95566 (SL = 16.1 mm) is excluded here. Values are proportions of standard length (SL) and head length (last five measurements), respectively, means and the first standard deviation (SD).

Status Coll.No.	Holotype Paratype NMW 95078 NMW 95565	Paratype MNHN 2006-1699	Paratype BMNH 2006.10.6.2	MEAN (±SD)
SL (mm)	30.1 23.4	32.3	29.6
Snout to first dorsal-fin origin	37.9 35.4	36.9	38.1	37.0 (1.3)

TABLE 5. Fin counts of holotype and four paratypes of Gobiodon irregularis sp. nov. from the northern Red Sea. d = damaged.

Status Coll. No.	Holotype NMW 95078	Paratype NMW 95565	Paratype NMW 95566	Paratype Paratype MNHN 2006-1699 BMNH 2006-10.6.2
D1	VI	VI	VI	VI VI
D2	11	11	11	10 11
A	9	10	9	9 9
C (segmented)	16	17	d	15 16
C (branched)	17	17	d	17 17
P	20	20	20	20 20
V	I/5 + I/5	I/5 + I/5	I/5 + I/5	I/5 + I/5 I/5 + I/5