A new species of Hetereleotris (Teleostei: Gobiidae) from the Socotra Archipelago (north-western Indian Ocean), a rare case of a hole-associated adaptation in gobiid fishes

Abstract

A new cryptobenthic gobiid species Hetereleotris nasoramosa sp. nov. is described based on the holotype and five paratypes collected from the northeastern part of Socotra Island, Arabian Sea, from moderately large pieces of coral rocks with holes at depths of 8-11 m. Molecular phylogenetic analysis placed the new species within the genus Hetereleotris. Hetereleotris nasoramosa sp. nov., differs from all species of Hetereleotris in having developed tentacles extending from each anterior and posterior nostril and five transverse suborbital papillae rows (instead four or six in other species). The new species superficially resembles the recently described Red Sea endemic species Cerogobius petrophilus by having forward-set, elevated eyes, a short snout, a moderately large mouth, a relatively deep and short caudal peduncle, and developed tentacles on the head, but differs from it by the same characters of developed tentacles extending from each anterior and posterior nostril and five transverse suborbital papillae rows as from other Hetereleotris species. Both species also share a specific habitat preference for tight holes in rock covered by micro-algae. A full description of the species is provided as well as a revised key to the species of Hetereleotris.

Full text

https://doi.org/10.11646/zootaxa.4996.2.3
http://zoobank.org/urn:lsid:zoobank.org:pub:C3724D94-327B-4701-9D97-30D98D8B4F18
284 Accepted by B. Frable: 9 Jun. 2021; published: 5 Jul. 2021
Article ZOOTAXA
ISSN 1175-5326 (print edition)
ISSN 1175-5334 (online edition)
Zootaxa 4996 (2): 284–300
https://www.mapress.com/j/zt/
Copyright © 2021 Magnolia Press
A new species of Hetereleotris (Teleostei: Gobiidae) from the Socotra Archipelago
(north-western Indian Ocean), a rare case of a hole-associated adaptation in gobiid
fishes
MARCELO KOVAČIĆ1, SERGEY V. BOGORODSKY2,3, UWE ZAJONZ2,4 & LUKE TORNABENE5
1Natural History Museum Rijeka, Lorenzov prolaz 1, HR–51000 Rijeka, Croatia.
2Senckenberg Research Institute and Museum of Nature (SMF), Section Ichthyology & Senckenberg Biodiversity and Climate Research
Centre (SBiK-F), Biogeography – Senckenberganlage 25, 60325 Frankfurt am Main, Germany.
�
eco-coasts@web.de; https://orcid.org/0000-0001-6106-1411
3Station of Naturalists, Omsk, Russia.
�
ic187196@yandex.ru
4Institute for Ecology, Diversity and Evolution, Faculty of Biological Sciences, Goethe University Frankfurt am Main, Max-von-Laue-
Straße 13, 60438 Frankfurt am Main, Germany;
5School of Aquatic and Fishery Sciences and the Burke Museum of Natural History and Culture, University of Washington, 1122 NE
Boat Street, Seattle, WA 98105, USA.
�
luke.tornabene@gmail.com; https://orcid.org/0000-0002-0673-2320
1Corresponding author.
�
marcelo@prirodoslovni.com; https://orcid.org/0000-0002-4049-9366
Abstract
A new cryptobenthic gobiid species Hetereleotris nasoramosa sp. nov. is described based on the holotype and five
paratypes collected from the north-eastern part of Socotra Island, Arabian Sea, from moderately large pieces of coral rocks
with holes at depths of 8–11 m. Molecular phylogenetic analysis placed the new species within the genus Hetereleotris.
Hetereleotris nasoramosa sp. nov., differs from all species of Hetereleotris in having developed tentacles extending from
each anterior and posterior nostril and five transverse suborbital papillae rows (instead four or six in other species). The
new species superficially resembles the recently described Red Sea endemic species Cerogobius petrophilus by having
forward-set, elevated eyes, a short snout, a moderately large mouth, a relatively deep and short caudal peduncle, and
developed tentacles on the head, but differs from it by the same characters of developed tentacles extending from each
anterior and posterior nostril and five transverse suborbital papillae rows as from other Hetereleotris species. Both species
also share a specific habitat preference for tight holes in rock covered by micro-algae. A full description of the species is
provided as well as a revised key to the species of Hetereleotris.
Key words: Arabian Sea, phylogenetic analysis, endemics, cryptobenthic species
Introduction
The genus Hetereleotris Bleeker, 1874 includes cryptobenthic small-size, marine gobies not exceeding 6 cm in total
length. Species of Hetereleotris typically display cryptic behavior, and are distributed in coastal waters in the Indo-
West Pacific in the depth range of 0.2–53 m, with most species living in shallow waters. Smith (1958) reviewed
the western Indian Ocean gobiid fishes and treated three species in Hetereleotris. Later, Hoese (1986) revised the
genus and recognized 13 valid species. Since Hoese’s revision, six additional species were described in the genus
(Gill 1998; Shibukawa 2010; Kovačić & Bogorodsky 2014; Kovačić et al. 2014; Kovačić et al. 2019a). The genus
Pascua was erected by Randall (2005) for his new species P. caudilinea Randall, 2005. It was placed in synonymy
with Hetereleotris by Hoese & Larson (2005). Randall (2006) and Shibukawa (2010) did not follow this synonymy
and the present authors provisionally recognize Pascua as valid until phylogenetic analysis verifies its relationship.
The new genus Cerogobius Kovačić, Bogorodsky, Troyer & Tornabene, 2019 was created for the Red Sea endemic
species C. petrophilus Kovačić, Bogorodsky, Troyer & Tornabene, 2019, which is morphologically largely similar
to Hetereleotris but differs by having a prominent tentacle on the snout between the nostrils. Also, its habitat prefer-
ence for holes in stones as hide-outs was considered unique at that time.

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Nine species of Hetereleotris are known from the Red Sea and Arabian Sea. Zajonz et al. (2019) listed 42 spe-
cies of gobiid fishes from the Socotra Archipelago including two species of Hetereleotris, H. vulgaris (Klunzinger,
1871) and H. zonata (Fowler, 1934). During two field trips performed for a UNEP-GEF conservation and develop-
ment project (#5347), the first in spring of 2018 to the main island Socotra, and the second in spring of 2019 cov-
ering four islands (Abd al-Kuri, Samha, Darsa, and Socotra), several goby specimens that occupied tight holes in
stones, were collected. Specimens were provisionally assigned to Cerogobius as they had developed tentacles on the
head and had the same habitat preference. The specimens share a specific feature of Cerogobius and Hetereleotris:
a gill cover joined with the lower limb of the first gill arch by membrane. Close examination revealed a singular
combination of characters, yet intermediate between Cerogobius and Hetereleotris, hinting at a new species. Sub-
sequent molecular phylogenetic data showed that the putative new taxon is nested within Hetereleotris, therefore it
is described in the present article as a new species of that genus. The current description raises the number of valid
species in the genus Hetereleotris to 20. We provide a revised key to all known species.
Materials and Methods
The majority of recorded specimens were observed and/or collected during two field surveys on Socotra Archi-
pelago conducted for the project ‘Support to the Integrated Programme for the Conservation and Sustainable Devel-
opment of the Socotra Archipelago, Yemen’, co-executed by the Senckenberg Biodiversity and Climate Research
Centre (SBiK-F) and the Environment Protection Authority of Yemen (EPA) for the United Nations Environment
Programme (UNEP) based on funds of the Global Environment Facility (GEF #5347). The EPA also issued the
research and export permit. The first survey took place from 23 April to 21 May of 2018 and the second from 21
March to 23 April 2019.
Morphometric methods follow Kovačić et al. (2014). Measurements smaller than 20 mm were taken with in-
teractively selected points in the Olympus cellSens Entry 2.2. software using the SC180 camera and U-TV0.5XC-3
camera adapter on the stereomicroscope SZX10 of the same producer, while those out of this range were taken with
digital callipers to a resolution of 0.01 mm viewed under stereomicroscope magnification. The length of the speci-
mens is presented as standard length + caudal-fin length. Standard length (SL) is measured from the median anterior
point of the upper lip to the base of the caudal fin (posterior end of the hypural plate). Morphometric data are given
as a ratio in the text and as percentages of SL in Table 1. The distances between landmarks based just on the soft
tissue i.e. without bone supports could be influenced by the various methods of original preservation i.e. in 70%
(paratypes, SMF 39501 and SMF 39503) and 95% ethanol (holotype, SMF 39500 and paratypes PMR VP4890 and
PMR VP4891). Terminology of the lateral-line system follows Sanzo (1911) and Miller (1986). External morphol-
ogy was studied on the holotype, SMF 39500 and four paratypes, excluding the paratype SMF 39502, which was
cleared and stained for osteology before the beginning of the study. The specimens were reversibly stained in 2%
solution of Cyanine Blue in distilled water (Saruwatari et al. 1997) to count for scales and sensory papillae rows.
Helicon Focus 7.0.2 was used, when necessary, for focus stacking software to reach acceptably sharp microphotog-
raphy from combined images. The cleared and stained paratype SMF 39502 was prepared following the protocol of
Dingerkus & Uhler (1977). Osteological terminology follows Birdsong et al. (1988).
The DNA was extracted from the holotype and two paratypes (PMR VP4891, PMR VP4890) using a Qiagen
®DNAeasy Blood and Tissue Kit (Qiagen, Valencia, California). DNA was also extracted from several specimens
of Hetereleotris vulgaris and a specimen of H. zonata, all from Socotra. For each of these samples, the nuclear genes
Rag1, Zic1, and sreb2 were amplified and sequenced using primers and PCR conditions described by Agorreta et
al. (2013). The mitochondrial gene cytochrome b was unsuccessfully amplified for these samples, and success with
the nuclear genes varied across samples as well (see Table 2; new sequences are deposited on GenBank). Sequences
of gobiid species were combined from Agorreta et al. (2013) and Kovačić et al. (2019b), which included the three
nuclear genes above, as well as the mitochondrial loci cytochrome b, and a mitochondrial ribosomal fragment
containing partial 12S, tRNAVal, and partial 16S. We conducted a phylogenetic analysis in MrBayes version 3.2
(Ronquist et al. 2012), partitioning by locus. Substitution models were chosen using PartitionFinder2 (Lanfear et
al. 2017) based on the Akaike Information Criterion. Two Metropolis-coupled Markov Chain Mone Carlo (MCMC)
runs, each consisting of 4 chains, were run for 20 x106 generations, sampling every 1000 generations. Burn-in, con-
vergence and mixing were confirmed by assessing likelihood scores in the program Tracer, and by visually inspect-
ing consensus trees from both runs.

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TABLE 1. Morphometric characters (% SL) of Hetereleotris nasoramosa sp. nov. Characters are sorted in alphabetic
order. Non-overlapping ranges between male and females marked with *.
Specimen SMF 39500
holotype
PMR VP4890
paratype
PMR VP4891
paratype
SMF 39503
paratype
SMF 39501
paratype
Sex female male female male female
Standard length (mm) 20.9 22.3 18.6 21.1 24.9
Base of the anal fin 28.1 27.7 26.1 29.0 27.1
Base of the second dorsal fin 36.0 34.1 35.0 33.3 36.1
Body depth (at the anal-fin origin) 17.8 16.4 15.9 16.7 16.1
Body depth (at the origin of pelvic fins) 21.4 19.3 19.5 18.5 19.7
Body width (at the origin of pectoral fins) 17.3 15.7 16.1 15.8 16.0
Caudal-fin length 23.1 22.7 23.4 21.1 21.1
Caudal peduncle depth* 12.4 11.2 11.4 10.7 12.2
Caudal peduncle length 11.5 11.8 10.3 11.4 10.8
Distance between first and second dorsal-
fin origins
18.1 18.3 18.6 18.8 18.6
Eye diameter 7.4 8.0 8.1 7.6 7.5
Head depth 19.7 19.7 19.4 19.7 19.4
Head length 29.9 31.0 29.8 29.3 29.5
Head width 21.4 20.3 20.1 20.2 20.8
Pectoral-fin length 16.6 17.4 17.1 17.7 15.9
Pelvic-fin length 15.6 15.5 15.6 16.6 14.9
Preanal-fin length* 61.1 55.1 59.8 55.2 59.5
Predorsal length 37.1 36.8 35.1 34.6 36.9
Prepelvic length 28.5 28.2 31.1 30.9 28.3
Snout length 3.9 4.0 3.8 3.6 3.8
Third dorsal-fin spine length 12.6 11.6 12.0 11.4 11.2
Third from last segmented anal-fin ray
length*
12.1 13.8 11.8 13.5 12.8
Third from last segmented dorsal-fin ray
length*
13.4 14.3 13.8 14.4 12.8
TABLE 2. GenBank accession numbers and vouchers for samples sequenced in this study.
Genus Species Sample
Number
Catalog
Number
Locality GenBank
Rag1
GenBank
sreb2
GenBank
zic1
Hetereleotris nasoramosa SOC18-191 SMF 39500
(holotype)
Socotra MW331513 MW331521 MW331528
Hetereleotris nasoramosa SOC19-355 PMR VP4890 Socotra MW331514 NA NA
Hetereleotris nasoramosa SOC19-358 PMR VP4891 Socotra MW331515 NA MW331529
Hetereleotris vulgaris SOC18-167 PMR VP4930 Socotra NA MW331526 MW331534
Hetereleotris vulgaris SOC18-223 SMF uncat. Socotra MW331518 MW331524 MW331532
Hetereleotris vulgaris SOC18-224 SMF uncat. Socotra MW331519 MW331525 MW331533
Hetereleotris vulgaris SOC18-225 SMF 39505 Socotra MW331517 MW331523 MW331531
Hetereleotris vulgaris SOC18-69 PMR VP4931 Socotra MW331516 MW331522 MW331530
Hetereleotris zonata SOC19-365 SMF 39507 Socotra MW331520 MW331527 MW331535

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Results
Generic identification
The following combination of morphological characters distinguishes members of the genus Hetereleotris from
other known gobiid genera (Kovačić et al. 2019a): 1) lower limb of first gill arch partially joined to gill cover by
membrane to one-half or more; 2) pelvic fins completely separated and without frenum (not included in Hoese’s
(1986) original diagnosis, just mentioned as common by Hoese since the character is variable in only one species of
Hetereleotris, H. zanzibarensis (Smith, 1958)); 3) suborbital papillae pattern transverse, usually with four suborbital
rows present in all Hetereleotris species with described or illustrated cephalic sensory systems, except for presently
described species that possesses five suborbital transverse rows and H. georgegilli Gill, 1998 that possesses six sub-
orbital transverse rows (Gill 1998) (all Hetereleotris species have transverse suborbital rows generated from row c
and no longitudinal row a, and the three Pascua species have longitudinal row a present and transverse suborbital
rows generated from row c absent, visible on Figure 2 in Hoese & Larson (2005) and on Figure 1 in Randall (2005));
4) no horn-like unpaired tentacle at the level of nostrils on the snout midline. The excluded characters for Hetereleo-
tris from Hoese (1986) and the added characters based on Kovačić et al. (2019b) were explained in Kovačić et al.
(2019a). The phylogenetic data support the placement of the new species in Hetereleotris (see below).
Molecular phylogenetics
The molecular phylogenetic analysis (Fig. 1) shows the new species nested within a clade containing Hetereleotris
zonata, H. vulgaris, and Cerogobius petrophilus, with strong support (Bayesian posterior probability = 1.0). Within
this clade, the new species is sister to a clade containing H. vulgaris and C. petrophilus. The phylogenetic placement
of the new species supports its inclusion in the genus Hetereleotris, and indicates that C. petrophilus may actually
represent a species of Hetereleotris. The phylogenetic analysis also recovers one specimen of H. vulgaris from
Saudi Arabia, Red Sea (sample KAU17-122) being somewhat divergent from other samples from Saudi Arabia and
Socotra Island. It is hence possible that a cryptic species exists within H. vulgaris. This should be further explored
by a comprehensive assessment of that species throughout its range, which spans broadly from the Red Sea, Gulf
of Oman, and the Arabian/Persian Gulf, south along coast of the eastern Africa to islands of the Western Indian
Ocean.
Hetereleotris nasoramosa sp. nov.
Socotra hole-hiding goby
Figs. 2–5, Table 1
Holotype. SMF 39500 [sample tissue SOC18-191], female, 20.9+4.8 mm, Socotra Island, Delisha, 12°40.312’ N,
54°09.212’ E, a small stone on sand flat, depth 11–12 m, coll. S.V. Bogorodsky & F.N. Saeed, 05 May 2018 (Fig.
4A & B).
Paratypes (5 specimens, 18.6–24.9 mm SL). PMR VP4890 [sample tissue SOC19-355], male, 22.3+5.1 mm,
Socotra Island, Di Hamri, 12°40.046’ N, 54°10.758’ E, a small rock, depth 8–10 m, coll. S.V. Bogorodsky, 02 April
2019; PMR VP4891 [sample tissue SOC19-358], female, 18.6+4.3 mm, Socotra Island, Di Hamri, 12°40.046’ N,
54°10.758’ E, a small rock, depth 8–10 m, coll. S.V. Bogorodsky, 02 April 2019; SMF 39501, female, 24.9+5.3
mm, Socotra Island, Di Hamri, 12°40.046’ N, 54°10.758’ E, a small rock, depth 8–10 m, coll. S.V. Bogorodsky, 02
April 2019 (Fig. 5A & B); SMF 39502, presumably male, 20.7+4.6 mm, Socotra Island, Di Hamri, 12°40.046’ N,
54°10.758’ E, a small rock, depth 8–10 m, coll. S.V. Bogorodsky, 02 April 2019; SMF 39503, male, 21.1+4.5 mm,
Socotra Island, Di Timri, 12°37.215’ N, 54°17.202’ E, rocky ridge with large stones, depth 10 m, coll. S.V. Bogoro-
dsky, 08 April 2019 (Fig. 5C).
Diagnosis. Dorsal-fin rays VI+I,12; anal-fin rays I,11; pectoral-fin rays 15–16, all rays branched; pelvic-fin
rays I,5, fins separated and without frenum, fifth ray unbranched; anterior nostril a moderately long tube with the
process extending from median side of rim (as tentacle longer than tube) or as a slender flap slightly shorter than

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tube; posterior nostril a long tube with two tentacles, anterior long and posterior shorter; no tentacle above eye;
mouth moderately large, posterior angle of jaws behind vertical through posterior edge of eye; no opercular spine;
small mental frenum present; pelvic fins ending distantly well in front of anus; head and body mainly naked except
for several ctenoid scales on caudal peduncle at caudal-fin base; head with anterior oculoscapular canal and preoper-
cular canal, posterior oculoscapular canal absent; anterior oculoscapular canal pores with erected rim; suborbital
rows of papillae in five transverse rows; nearly rounded dark blue or blackish spot as large as pupil above opercle;
a large irregular white blotch on postorbital head, cheek and lower preopercle.
FIGURE 1. Bayesian molecular phylogenetic analysis based on combined mtDNA and nuclear genes. Colored circles at nodes
depict posterior probability support values. Nodes with support less than 0.50 are collapsed into polytomies. Names of lineages
follow Agorreta et al. (2013).

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FIGURE 2. Hetereleotris nasoramosa sp. nov., holotype, SMF 39500 [sample tissue SOC18-191], female, 20.9 mm SL, Di
Hamri, Socotra Island: A: head with AN - anterior nostril as a short tube with tentacle from the rim, PN - posterior nostril a long
tube with very long anterior tentacle and shorter posterior tentacle extending from the rim, PAJ - posterior angle of jaws extends
behind vertical through posterior edge of eye; B: pelvic fins completely separated and without frenum; C: caudal peduncle
stained, with visible scales; D: nape stained, erected pores of anterior oculoscapular canal, terminology in text. Photos by S.V.
Bogorodsky (A) and M. Kovačić (B-D).
Description (The morphometric values in the text are presented first for the holotype followed by ranges for
paratypes; meristic values, if variable, the same). Body elongate, depth at anal-fin origin 5.6 (6.0–6.3) in SL, later-
ally compressed posteriorly, caudal peduncle deep and short, caudal peduncle depth 1.4 (1.3–1.4 female paratypes,
1.5–1.6 male paratypes) of body depth at anal-fin origin, caudal peduncle depth 0.9 (0.9 female paratypes, 1.1 male
paratypes) of caudal peduncle length (Fig. 4). Head of moderate size, its length 3.4 (3.2–3.4) in SL, width 4.7 (4.8–
5.0) in SL, depth 5.1 (5.1–5.2) in SL, not depressed, its depth 1.1 (1.0–1.1) of width. Snout very steep in profile from
lateral view, and short, length 0.5 (0.5) of eye diameter, 7.7 (7.7–8.1) in head length, no unpaired horn-like tentacle
at the level of nostrils on snout midline. Anterior nostril a moderately long tube set over tip of upper lip with process
extending from median side of rim (as tentacle longer than tube) or as slender flap slightly shorter than tube. Pos-
terior nostril long tube, with tentacle longer than tube extending from anterior side of rim and tentacle shorter than
tube extending from posterior side of rim (Fig. 2A). Eyes dorsolateral, moderately large, eye diameter 4.0 (3.7–4.0)
in head length, orbit projecting forward and slightly elevated above dorsal profile of head. Interorbital narrow, 4.4
(4.1–5.3) of eye diameter. No tentacle above eye. Nape straight and flat. Mouth slightly subterminal, oblique, jaws
ending anteriorly unequally, lower jaw slightly retracted anteriorly. Mouth moderately large, posterior angle of jaws
behind vertical through posterior edge of eye. Upper lip wider than cheek, slightly inflated, in preserved specimens
flattened and extending upwards on cheek. Cheek very narrow, suborbital depth less than upper lip width. Each side
at front of upper jaw with outer row of 4–5 large recurved caniniform teeth, followed by irregularly scattered band
of small conical inner teeth. Side of jaw with a single lateral row of about 10 medium-sized caniniform teeth. Sides

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of front of lower jaw with outer row of 4–5 large caniniform teeth, followed by irregularly scattered band of small
conical median teeth and inner row of 5–6 large widely-spaced caniniform teeth. Single row of about ten medium-
sized caniniform teeth continuous laterally on side of jaw. Small mental frenum midventrally behind lower lip.
Branchiostegal membranes fused from isthmus to below pectoral-fin base, gill openings restricted to pectoral-fin
base. Most of lower limb of first gill arch joined to gill cover by membrane. No spines on preopercle.
FIGURE 3. Hetereleotris nasoramosa sp. nov. Cephalic sensory papillae, paratype, PMR VP4890, male, 22.3 mm SL, Di
Hamri, Socotra Island. The right side illustrated, as it is in better condition, terminology in text. Drawing by M. Kovačić.
Fins. First dorsal fin with VI spines, second dorsal fin I,12; anal fin I,11; branched caudal-fin rays 15, segmented
17 (16:1, 17:3). Pectoral-fin rays left 16 and right cut (15:4, 16:2, right side cut in two paratypes), all rays branched,
not free at tips. Pectoral girdle without flaps on anterior edge. Pelvic fins I,5+5,I, left and right fin completely sepa-
rated, distant and without frenum (Fig. 2B). Pelvic-fin rays branched, except fifth ray, fourth ray the longest, rays
progressively shorter towards the first ray and pelvic spine. Spines of first dorsal fin not elongate or filamentous,
first to fifth spine of first dorsal fin about equal in length, third always slightly longer than others, sixth spine short;
fourth or fifth to sixth spine of first dorsal fin barely reaching origin of second dorsal fin when folded down. Origin
of first dorsal fin behind vertical at pectoral-fin base. Origin of anal fin posterior to vertical at origin of second dorsal
fin, i.e. opposite about first segmented ray of second dorsal fin. Pectoral fins not reaching posteriorly to below origin
of second dorsal fin or just reaching to vertical at the second dorsal-fin spine. Pelvic fins short, ending well in front
of anus in both sexes, 0.6 (0.6–0.7) of distance between origin of fins and anus, shorter than pectoral fins, 0.9 (0.9)
of pectoral-fin length. Caudal fin rounded, shorter than head, 1.3 (1.3–1.4) in head length.
Squamation. Head and body naked except for several ctenoid scales on caudal peduncle at caudal-fin base: four
to eight scales ventrally on lateral side and one scale on the dorsal lateral side, most specimens with one more scale
midlaterally (Fig. 2C).
Cephalic sensory systems (Figs. 2D & 3). Head with anterior oculoscapular canal and preopercular canal with
pores σ, λ, κ, ω, α, ρ, and δ, ε respectively. Pores in anterior oculoscapular canal with erected rim, nearly short
tubes in some specimens (e.g. holotype) (Fig. 2D). Pore ω distant from eye, pore ρ positioned quite dorsally close
to the level of pore ω, pore β absent. Posterior oculoscapular canal absent. Rows of head sensory papillae counted
on all types, at least one side was in sufficient condition to count (holotype with better right side used for Fig. 3).
Preorbital rows: snout with four median preorbital series, upper row r (1–2) middorsally between eyes above pore
σ and posterior nostrils, row s1 (1) at posterior nostril, row s2 (1) below posterior nostril and row s3 (2–3) above up-
per lip (rows s1 and s2 on Fig. 3 hidden by nostrils and tentacles). Lateral series c on snout in four parts, superior

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rows: upper row c2 (2) between anterior and posterior nostrils, lower row c1 (2–3) at anterior nostril; inferior rows:
upper horizontal c2 (3) anteriorly, and lower horizontal c1 (1–2) posteriorly above upper lip. Suborbital rows: row a
absent; row b short, behind vertical of posterior edge of eye and anteriorly close to suborbital row 4; five transverse
suborbital rows of sensory papillae (1–5) present, row 1 oblique, reaching upper lip, rows 2 and 3 short and distant
from eye, close to row d, row 4 long, curved, from posterior edge of eye slanting to posterior end of row d or slightly
below it, row 5 close to pore α (1: 6–9, 2: 4–5, 3: 5–7, 4: 13–19, 5: 4); row d (6+10 – 7+13) long, above posterior
part of upper lip, and continuing on lower cheek to meet suborbital row 4. Preoperculo-mandibular rows: external
row e (14+10 – 18+18) longitudinal and uniserial, divided into anterior and posterior sections; internal row i (7+8
– 10+8) longitudinal and uniserial, divided into anterior and posterior sections, mental row f (4) behind frenum.
Oculoscapular rows: three larger papillae longitudinally arranged on position of missing posterior oculoscapular
canal above opercle, marked poc. Anterior longitudinal row x1 (3+1 – 4+3) above level and behind pore ρ, divided
in two parts, posterior longitudinal row x2 (3) above posterior opercular edge, transverse row z (7–10) below and
anterior to pore ρ, row y (1) below and behind row x2. Transverse axillary rows as1 (3) and as2 (2–3) and as3 (1–2)
present, row la 1 (2) above between rows as1 and as2 not visible in all specimens and la 2 not present (row as3 on Fig.
3 hidden by pectoral fin). Opercular rows: single papilla at location of missing pore γ, marked pc. Transverse row
ot (11–13); superior longitudinal row os (4–5); and inferior longitudinal row oi (3) not visible in every specimen.
Anterior dorsal rows: transverse row n (3–4) behind pore ω, rows o and m absent; row g longitudinal (6–8); row h
(3–5) in front of the first dorsal-fin base.
Osteology. There are 10 precaudal vertebrae and 17 caudal vertebrae. The dorsal-fin pterygiophore pattern is
3-22110.
FIGURE 4. Hetereleotris nasoramosa sp. nov., holotype, SMF 39500, female, 20.9 mm SL, Di Hamri, Socotra Island: A:
freshly collected specimen; B: preserved specimen. Photos by S.V. Bogorodsky (A) and M. Kovačić (B).

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FIGURE 5. Hetereleotris nasoramosa sp. nov.; A: SMF 39501, paratype, female, 24.9 mm SL, alive specimen, Di Hamri,
Socotra Island; B: the same specimen, freshly collected; C: paratype, SMF 39503, male, 21.1 mm SL, alive specimen, Di Timri,
Socotra Island; D: presumably male, alive specimen, not collected, Di Timri, Socotra Island. Photos by S.V. Bogorodsky.

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Color of fresh and live female (Fig. 4A, holotype, SMF 39500; Fig. 5A & B, SMF 39501). Body in life trans-
parent, with numerous yellow-brown or brown dots, a series of six or seven short, double, saddle-like dark brown
marks along back, four series of 2–5 irregular iridescent white marks alternating with dark brown dashes along ver-
tebral column, and five series of reflected white spots ventrally on body visible in alive specimens, the first series
as 4–5 spots on abdomen, the last, fifth series as 1–2 very small spots above posterior part of anal fin; two obscure
dusky blotches on abdomen, first beneath the pectoral fin, the second just behind it. An obvious nearly rounded dark
blue to blackish spot as large as pupil above opercle over posterior opercular edge at the level of the pupil is most
striking coloration pattern. Head brown, darker anteriorly, with a large oblique, irregular, white blotch on postorbital
head and most of cheek, with ventroposterior extension ending at lower edge of preopercle; behind large blotch sev-
eral smaller whitish spots of various size and shape present over preopercle and opercle and on nape and predorsal
area, and a small white spot at angle of jaws; head covered with dark brown to blackish dots, becoming black and
more dense on cheek and preopercle. First dorsal fin with two brown oblique bands, one in outer part, another short
in the middle of fin from first to fourth spine, with white rectangular mark at base of first two spines and oblique
white band between two brown bands, tips from fourth to sixth spines white. The second dorsal fin with transparent
membranes and greenish brown spine and rays, with white dots on rays forming three irregular oblique rows. Anal
fin mostly transparent with widely scattered small melanophores, mostly at base. Caudal fin transparent, with green-
ish rays, clearly visible in freshly dead specimens, and melanophores mostly at the fin base. Pectoral-fin base within
a large white blotch, extending on base of fin except between sixth to eighth rays, rest of fin transparent, yellow in
freshly dead specimens. Pelvic fins dark brown, densely dotted with melanophores.
The overall live surface coloration pattern is retained in freshly dead specimens, with white marks on body less
obvious and brown dotted coloration more obvious than in live specimens. Iris mottled brown with four faint radiat-
ing orange-red bars, pupil green-black. Body opaque white, with scattered melanophores concentrated in six double,
short, brown bars along dorsal-fin bases, two below the first dorsal fin and four below the second dorsal fin.
Color of live male (Fig. 5C, paratype, SMF 39503, Fig. 5D). Material is limited, hence sexual dichromatism
cannot be confirmed. Based on photograph of a male (Fig. 5C), head is not darker anteriorly than rest of the head
as in the female, black spot above posterior edge of opercle is faint, a single white blotch on abdomen (vs. series of
clusters of reflected white spots ventrally on body in females), and two dark bands on first dorsal fin are indistinct.
Color of preserved specimens (Fig. 4B): Coloration lost in preservation, body yellowish white, with dark brown
dots from melanophores. No sexual dichromatism observed. Head dotted brown. Ventral side and mouth darker
than rest of head. Large oblique irregular whitish marking behind and below eye. Smaller whitish spots of various
size and shape on head opercle, preopercle, dorsal and ventral side, not prominent, formed by less dense pattern of
melanophores compared to darker parts. Eye with dark iris and white pupil. Body with scattered melanophores more
concentrated in dorsal part, six marks along both dorsal-fin bases and ill-defined marks along lateral midline recog-
nizable in some specimens. Intensive dark brown rounded mark above posterior opercular edge and pectoral fin is
most conspicuous coloration pattern. Breast brown with many melanophores, rest of ventral side of body with more
broadly spaced melanophores. First dorsal fin with two dark oblique bands, one in upper part, one in the middle of
fin, alternating with whitish mark at anterior corner of fin base and oblique white band between two brown bands.
Second dorsal fin marbled with dark and white spots. Anal fin transparent with rarely scattered small melanophores
mostly at base. Caudal fin transparent, with melanophores at the fin base. Pectoral fins with few scattered melano-
phores, the rest of fin transparent. Pelvic fins dark dotted with melanophores.
Etymology. The specific name nasoramosa is formed from the combination of two Latin words naso (nose),
and ramosa (branched) in reference to the well-developed, branched process extending from the rim of the anterior
and posterior nostril, respectively.
Habitat and Distribution. Specimens of H. nasoramosa were collected on rubble-sand patches in sandy areas
and in areas with mixed corals and stones or rocks at several localities from the north-eastern part of the Socotra
Island. The holotype and paratypes were found living inside small holes in moderately large pieces of coral rock
covered with short algae at depths of 8–11 m. The species has not yet been recognized from elsewhere and appears
to be endemic to the Socotra Archipelago.
Remarks. Based on the molecular phylogeny and several diagnostic morphological characters (see Generic
identification above), the new species was assigned to Hetereleotris. It is unique though among Hetereleotris spe-
cies in having a simple tentacle or slender flap extending from the anterior nostril and anterior and posterior ten-
tacles extending from the posterior nostril, and by having five suborbital transverse papillae rows. An obvious large

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(as large as pupil), dark spot above the opercle is shared only with H. bipunctata Tortonese, 1976 and H. margare-
tae Hoese, 1986. However, both latter species have coloration patterns distinguishing them from the new species.
Among twenty Hetereleotris species presently recognized, only the new species and H. tentaculata (Smith, 1958)
share forward-set elevated eyes, a very short snout, and the posterior angle of the jaws behind vertical through the
posterior edge of eye. The combination of head canals and pores seen in the new species is present otherwise only
in H. caminata (Smith, 1958), H. tentaculata and H. vulgaris. The ctenoid scales, restricted to caudal peduncle only
as a ventral patch and one or two individual scales dorsally, was reported among Hetereleotris species only in some
specimens of H. tentaculata by Hoese (1986), in which it is variably present. The extreme reduction to a few scales
is also present in H. aurantiaca Kovačić & Bogorodsky, 2019, but with a different pattern. All other Hetereleotris
species are more extensively scaled, at least on the caudal peduncle, or the body is completely scaleless. Hetereleo-
tris nasoramosa is morphologically most similar to H. tentaculata, sharing the following combination of characters:
dorsal-fin rays VI+I,12, anal fin rays I+I,11, presence of some kind of tentacles on the head, eyes forward-set and
elevated, a very short snout, posterior angle of jaws behind vertical through posterior edge of eye, scales restricted
to caudal peduncle in a similar pattern (at least in some H. tentaculata specimens), and the same pattern of head
canals and pores. However, H. tentaculata has a tentacle over the eye, no tentacles on the nostrils and a different
coloration, e.g. presence of a dark bar below first dorsal fin and absence of a dark humeral spot. The putatively close
relationship of these two species based on morphology should be confirmed once H. tentaculata material is avail-
able for molecular analysis.
Cerogobius petrophilus was described in its own genus based on the presumed distinctive presence of a single
tentacle on the snout midline between nostrils, with no other tentacles on the head. Compared to the new species,
C. petrophilus is scaleless, with head canals and pores absent, with four suborbital transverse papillae rows and a
different coloration (see Kovačić et al. 2019b). Its generic assignment is pending further investigation, as elaborated
below.
Artificial key to the identification of the described species of Hetereleotris
The key is modified from Hoese & Larson (2005) and Kovačić et al. (2019a) to accommodate the new species.
1a. An enlarged tentacle over eye (western Indian Ocean) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .H. tentaculata (Smith, 1958)
1b. No tentacle over eye. ...................................................................................2
2a. Anterior and posterior nostrils each with long process (tentacle) extending from the rim (Fig. 1B); 5 suborbital transverse papil-
lae rows (north-western Indian Ocean) ...................................................H. nasoramosa sp. nov.
2b. Anterior and posterior nostrils without processes from the rim; 4 or 6 suborbital transverse papillae rows.. ................3
3a. Body densely scaled or at least with scales on caudal peduncle. .................................................4
3b. Body completely scaleless. .............................................................................16
4a. Scales ctenoid, at least posteriorly on body .................................................................5
4b. Scales entirely cycloid. .................................................................................9
5a. Body with scales restricted to caudal peduncle; no head pores. ..................................................6
5b. Body completely or partly scaled, longitudinal scale count 10–30; head pores present ...............................7
6a. Body with 4–5 rows of scales restricted to caudal peduncle; operculum with 2 spines dorsally; body dusky grey with diffuse
dark bars on dorsal half (western Indian Ocean). . . . . . . . . . . . . . . . . . . . . . . . . . . . ..H. apora (Hoese & Winterbottom, 1979)
6b. Body with squamation reduced to a few scales on caudal peduncle at caudal-fin base; operculum without spines; body yellow-
ish orange, with five vertical brown bars (Red Sea) . . . . . . . . . . . . . . . . . . . . . . .H. aurantiaca Kovačić & Bogorodsky, 2019
7a. Scales restricted to posterior body, longitudinal scale count 10–13; six suborbital transverse papillae rows (Mauritius) ......
................................................................................H. georgegilli Gill, 1998
7b. Scales entire on body, longitudinal scale count 25–30; four suborbital transverse papillae rows ........................8
8a. Second dorsal-fin rays I,9; anal-fin rays I,8; pelvic-fin rays I,5; body scales mainly ctenoid; pelvic fins usually united to form
a disc; pore β present in anterior oculoscapular head canal (lateral canal pore LC1 of Hoese 1986); belly naked (western Indian
Ocean) ......................................................................H. zanzibarensis (Smith, 1958)
8b. Second dorsal-fin rays I,10; anal-fin rays I,9; pelvic-fin rays usually I,4, fifth ray sometimes present as a rudiment; ctenoid
scales from caudal-fin base to below middle of second dorsal fin; pelvic fins separated; pore β absent in anterior oculoscapular
head canal; belly scaled (western Indian Ocean) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H. vinsoni Hoese, 1986
9a. Black spot subequal to pupil diameter above rear edge of opercle ...............................................10
9a. No black spot above rear edge of opercle. ..................................................................11
10a. Second dorsal-fin rays I,12–13; anal-fin rays I,11–12; pectoral-fin rays 15; a black spot dorsally at posterior end of caudal pe-
duncle sometimes present; body scales small, longitudinal scale count 40–52; body slender, depth at anal-fin origin 6.7–7.1 in
SL (north-western Indian Ocean) ................................................ .H. bipunctata Tortonese, 1976

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10b. Second dorsal-fin rays I,11; anal-fin rays I,10; pectoral-fin rays 17; no black spot dorsally at end of caudal peduncle; body
scales large, longitudinal scale count 28–30; body more robust, depth at anal-fin origin 5.3–6.3 in SL (western Indian Ocean)
..............................................................................H. margaretae Hoese, 1986
11a. Scales restricted to caudal peduncle, longitudinal scale count 7–9; body covered with small dark spots (western Indian Ocean)
..........................................................................H. nebulofasciata (Smith, 1958)
11b. Body variably scaled but not restricted to caudal peduncle, longitudinal scale count 14–48; body without spots ..........12
12a. Body with obvious brown bar below first dorsal fin; head with brown band across interorbital area, continuing diagonally from
eye to corner of opercle. ...............................................................................13
12b. Body without bar below first dorsal fin; no band on head .....................................................15
13a. Second dorsal-fin rays I,11; head pores absent; scale pattern a long triangle tapering to nearly pectoral-fin base, longitudinal
scale count 29; moderately broad brown bar on caudal-fin base (Red Sea) . .H. semisquamata Kovačić & Bogorodsky, 2019
13b. Second dorsal-fin rays I,12–13; head pores present; scale pattern not tapering, covering most of body, longitudinal scale count
32–48; no bar on caudal-fin base. .........................................................................14
14a. Scales moderately large, longitudinal scale count 32–33; head with brown stripe from eye to middle of upper jaw (western
Indian Ocean) .......................................................................H. kenyae Smith, 1958
14b. Scales small, longitudinal scale count 35–48; no stripe between eye and upper jaw (western to central Indian Ocean). .......
............................................................................... H. zonata (Fowler, 1934)
15a. Second dorsal-fin rays usually I,9–11; anal-fin rays usually I,8–9; longitudinal scale count 32–25; head pores present (western
Indian Ocean to Japan) .............................................................H. poecila (Fowler, 1946)
15b. Second dorsal-fin rays usually I,12; anal-fin rays usually I,11; scales restricted to posterior body, longitudinal scale count
14–15; head pores absent (Japan). ...................................................H. exilis Shibukawa, 2010
16a. Head pores present ...................................................................................17
16b. Head pores absent. ...................................................................................18
17a. Posterior nasal tube elongate, about twice length of anterior nasal tube; second dorsal-fin rays usually I,12; pectoral-fin rays
usually 17–18; posterior opercular margin with dark bar (western Indian Ocean) . . . . . . . . . . . . . . H. caminata (Smith, 1958)
17b. Posterior nasal tube subequal to anterior tube; second dorsal-fin rays usually I,11; pectoral-fin rays usually 15–16; posterior
opercular margin with light edge (western to central Indian Ocean) . . . . . . . . . . . . . . . . . . . . . .H. vulgaris (Klunzinger, 1871)
18a. Posterior nasal tube slightly shorter than anterior nasal tube; transverse dark band below first dorsal fin (Red Sea). .........
............................................................................H. diademata (Rüppell, 1830)
18b. Posterior nasal tube 1/10–1/2 of length of anterior nasal tube; no transverse dark band below first dorsal fin .............19
19a. Dorsal fins with longitudinal dark submarginal band; second dorsal-fin rays I,12; anal-fin rays I,11 (Red Sea) .............
...............................................................H. dorsovittata Kovačić & Bogorodsky, 2014
19b. No longitudinal dark submarginal band on dorsal fins; second dorsal-fin rays I,10; anal-fin rays I,9 (Red Sea). ............
............................................................. H. psammophila Kovačić & Bogorodsky, 2014
Discussion
The only synapomorphy shared by all species of the genus Hetereleotris is the lower limb of first gill arch partially
joined to gill cover by membrane to one-half or more, as other diagnostic characters have one or two exceptions.
Beyond these, congeners display highly variable combinations of morphological characters. Species of the genus
may be divided into two large groups based on their squamation, five species with naked head and body and 15 with
the body covered in scales or with scales at least present on the caudal peduncle. Among four of those 15 species, H.
apora, H. aurantiaca and H. tentaculata share with H. nasoramosa ctenoid scales confined to the caudal peduncle.
Hetereleotris nebulofasciata also has scales restricted to caudal peduncle but all are cycloid. Another variable char-
acter is the presence or absence of head pores. Eleven species are characterised by having head pores whereas nine
species of Hetereleotris lack them. Only two species, H. nebulofasciata and H. tentaculata, have head pores and
scales confined to caudal peduncle, sharing both characters with H. nasoramosa. However, H. nebulofasciata, as
noted above, has cycloid scales and lacks a preopercular head canal. Another character, the pelvic-fin condition, is
less variable and useful as generic feature as all species have separate pelvic fins without frenum, only in H. zan-
zibarensis the fins can vary from forming a disc to completely separate. Species of Hetereleotris and Cerogobius
petrophilus possess transverse pattern of suborbital papillae rows with 4 rows in most species, except for 5 in H.
nasoramosa and 6 in H. georgegilli (Kovačić et al. 2019a). Species of the genus are variable in coloration with dif-
ferent patterns of spots, blotches and bars but only three species, H. bipunctata, H. margaretae and H. nasoramosa
have a dark spot as large as pupil above rear edge of opercle. Hetereleotris georgegilli has dark spot in that position
but the spot twice smaller.
The head shape and habitat use of H. nasoramosa is not usual in gobies. The new species superficially resembles
blennioid fishes in having the orbit set in a forward position, large eyes, a short snout, tentacles on the head, and a
mostly scaleless body. This obviously represents a convergent development associated with the preference for small

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holes as hide-outs. Individuals were observed with only the anterior half of the head being exposed outside the hole.
The presence of tentacles, which may imitate epilithic micro-algae, could serve to provide camouflage and mask the
species from predators and prey. Individuals of the blenny Alloblennius pictus (Lotan, 1970) were observed in the
same area, occupying holes in large pieces of rocks (Fig. 6B).
FIGURE 6. Resemblance of goby Hetereleotris nasoramosa sp. nov. to syntopic blenny Alloblennius pictus; A: H. nasoramosa
sp. nov., alive goby, female, SMF 39501, Di Hamri Socotra Island; B: A. pictus, male, Di Hamri Socotra Island. Photos by S.V.
Bogorodsky.
Herein Cerogobius petrophilus is kept in a separate genus, despite it nesting within the other Hetereleotris spe-
cies in molecular analysis, closer to H. vulgaris than to H. nasoramosa. Investigating the validity of Cerogobius and
the placement of C. petrophilus awaits further phylogenetic analysis that should include all or most Hetereleotris
species. Likewise, it will be critical to include the type species of the genus, H. diademata in a future comprehen-
sive phylogenetic analysis for determining which species remain within the genus and which will be assigned to
new or resurrected genera. The genus Hetereleotris is already moderately large and contains morphologically quite
variable species that can be divided into smaller subgroups based on some distinctive morphological traits. Several
studies have questioned the monophyly of the genus prior to the description of Cerogobius (reviewed by Kovačić
et al. 2019a). We expect that an integrative taxonomic analysis will lead to splitting the genus and might entail the
resurrections of genera described by Smith (1958) or retention of Cerogobius. The phylogenetic analysis should also
seek to clarify the status of the genus Pascua and its three recognised species.

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Morphologically, contrary to the present - though limited - phylogenetic results, the genus Cerogobius could be
expanded to include H. nasoramosa or even H. tentaculata. Living in holes like blennies and adapting to that habitat
by moving the eyes in front of the head, adjusting the general body form, and developing tentacles as camouflage,
or even also as sensory organs, is a major evolutionary adaption shared by H. nasoramosa and C. petrophilus, and
maybe even H. tentaculata. This raises doubts about the present phylogeny of a limited number of species, as this
phylogeny presumes either an evolutional reversal of a complex set of adaptations to a regular gobiid habitus in H.
vulgaris or an independent development in H. nasoramosa and C. petrophilus of these extended adaptations.
No sexual dimorphism was found among the examined specimens. However, the photographs of a live male
show more pale live coloration than in females (Fig. 5C compared to Fig. 5A), with an additional photograph of
an uncollected specimen of unidentified sex (Fig. 5D) having the same pale coloration. The two pale specimens
indicated that the paler pattern is present in the population, but this limited data provide no evidence for sexual
dichromatism. Paler pattern of males would be contrary to the usual sexual dichromatism found in gobies, where
males have darker coloration than females, present permanently or only during the mating season (see Kovačić et
al., 2020 and references there in).
All collected specimens of the new species were taken from the main Socotra Island. The Socotra Archipelago
lies in the north-western part of the Indian Ocean between 12°5’N and 12°43’N and 53°0’E and 54°35’E at the junc-
tion between the Gulf of Aden and the Arabian Sea. The Archipelago includes three smaller islands Darsa, Samha,
Abd al-Kuri, two islets Sabuniya and Kal Farun, and the main island of Socotra. The western-most island Abd al-
Kuri is separated from mainland Africa (Somalia) by the Socotra Passage, a narrow strip of water only 95 km wide,
and the eastern tip of Socotra Island is separated by 330 km from the nearest point at mainland Arabia (Yemen,
Ras Fartak). Zajonz et al. (2019) summarized all published and new data and provided a list of 682 species from
Socotra Archipelago, along with a working list of additional 51 Operational Diversity Units (see Zajonz et al. 2019:
104, Annex 2). Among the known species from Socotra only three fish species are endemic to the Archipelago, all
belonging to the family Pseudochromidae: Halidesmus socotraensis Gill & Zajonz, 2003, Pseudochromis chryso-
spilus Gill & Zajonz, 2011 and P. socotraensis Gill & Zajonz, 2011 (Gill & Zajonz 2003; Gill & Zajonz 2011).
Hetereleotris nasoramosa is the fourth endemic species for the Socotra Archipelago and the first endemic goby
for the area. As discussed earlier, most species of Hetereleotris have a restricted distribution range (Kovačić et al.
2019a). The Red Sea contains seven species of the genus and Cerogobius petrophilus, in contrast to neighbouring
areas of the Arabian region where three species are known from Oman waters (H. bipunctata, H. vulgaris and H.
zonata), three species from the Socotra Archipelago (H. nasoramosa, H. vulgaris and H. zonata), and only one spe-
cies was reported from the Gulf of Aden (H. bipunctata). An undescribed species, similar to C. petrophilus and H.
nasoramosa in having tentacles on the head and a hole-dwelling behavior, was photographed in the Gulf of Oman
(Fig. 7). It has very long, narrow, tubed posterior nostrils without tentacles, versus posterior nostrils with bifurcated
tentacles in H. nasoramosa.
Comparative material examined
Cerogobius petrophilus: PMR VP4501, female, 15.4+3.2 mm, Red Sea, Saudi Arabia, Thuwal, Al Fahal reef.
Hetereleotris aurantiaca: SMF 35966, female, 14.5+3.4 mm, Red Sea, Saudi Arabia, Jeddah, Obhur creek (Sharm Obhur).
Hetereleotris diademata: PMR VP2479, 1 female, 27.2+7.2 mm, Red Sea, Egypt, Hurghada.
Hetereleotris dorsovittata: SMF 35229, male, 21.7+6.3 mm, Red Sea, Saudi Arabia, Farasan Archipelago, Farasan
Island.
Hetereleotris psammophila: PMR VP3054, holotype, female, 26.9+7.3 mm, Red Sea, Gulf of Aqaba, Egypt, Dahab;
PMR VP3049, paratype, female, 26.8+7.0 mm, Red Sea, Gulf of Aqaba, Egypt, Dahab.
Hetereleotris semisquamata: PMR VP3053, female, 12.6 mm, caudal fin damaged, Red Sea, Southern Egypt, Shams
Alam.
Hetereleotris vulgaris: SMF 39504 [sample tissue SOC18-29], juvenile of unidentified sex, 13.1+3.7 mm, Socotra
Island, Di Hamri, 26 April 2018; PMR VP4931 [sample tissue SOC18-69], male, 22.7+6.1 mm, Socotra Island, Di
Hamri, 29 April 2018; PMR VP4930 [sample tissue SOC18-167], female, 23.8+5.7 mm, Socotra Island, Di Hamri,
03 May 2018; SMF 39505 [sample tissue SOC18-225], female, 18.8+4.6 mm, Socotra Island, Di Hamri, 10 May
2018; SMF 39506, female, 18.7+4.5 mm, Socotra Island, Di Hamri, 08 April 2019.

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Hetereleotris zonata: PMR VP2106, female, 29.7+7.3 mm and PMR VP2107, female, 33.6+8.2 mm, both
Indian Ocean, South Africa, Eastern Cape, Wild Coast, Coffee Bay, Hole-in-the-Wall; SMF 39507 [sample tissue
SOC19-365], female, 20.2+4.2 mm, Socotra Island, Di Hamri, 02 April 2019.
FIGURE 7. Hetereleotris sp., not collected, Fahal Island, Gulf of Oman, Oman. Photo by C. Semmens.
Acknowledgements
The field research, on which this study is based, was conducted for the project ‘Support to the Integrated Programme
for the Conservation and Sustainable Development of the Socotra Archipelago, Yemen’, under the auspices of the
United Nations Environment Programme and funded by the Global Environment Facility (#5347). The Environ-
ment Protection Authority Yemen is gratefully acknowledged for issuing the research and export permits. The na-
tional project manager Dr. Abdulkarim Nasher is cordially thanked for facilitating the local logistics and taking a
keen interest in the fish studies. We also wish to thank Moteah S. Aideed for his support during the field work and
dive operations. MK has been supported in part by the grant of the Croatian Science Foundation under the project
IP-2016-06-9884 and in part by the grant of the Croatian Science Foundation under the project IP-2016-06-5251.
The initial research on which this study is based was conducted under the auspices of the project ‘Conservation and
Sustainable Use of Socotra Archipelago’, led by the United Nations Environment Programme (UNEP) and funded
by the Global Environment Facility (GEF). We especially thank Fouad N. Saeed for his help during field work and
Christy Pattengill-Semmens (Reef Environmental Education Foundation) for the photograph of an unidentified
goby from the Gulf of Oman. We are grateful to Ronald Fricke for his advice concerning the species name formation
and interpreting the ICZN.
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