Lepadichthys erythraeus Briggs & Link 1963

Craig, Matthew T., Bogorodsky, Sergey V., Randall, John E. & Mal, Ahmad O., 2015, Lepadichthys bilineatus, a new species of clingfish from Oman (Teleostei: Gobiesocidae), with a redescription of Lepadichthys erythraeus Briggs and Link from the Red Sea, Zootaxa 3990 (1), pp. 113-122 : 117-121

Lepadichthys erythraeus Briggs & Link 1963

Figures 2–4 , Table 1

Lepadichthys erythraeus Briggs & Link 1963:102 (Hurghada (Al-Ghardaqa), Governorate, Egypt, Red Sea). Holotype, SMF 5586, 36.6 mm SL ( Fig. 2 ).

Lepadichthys erythraeus: Dor 1984: 54 (Red Sea); Goren & Dor 1994: 13 (Red Sea); Golani & Bogorodsky 2010: 45 (Red Sea).

Diagnosis. A species of Lepadichthys with a membrane joining dorsal and anal fins with the caudal fin; anus closer to anal fin than to disc, about two-thirds the distance from the rear margin of the disc to the origin of anal fin; upper attachment of gill membrane opposite ninth pectoral-fin ray; eight rakers on second gill arch; postdorsal-caudal distance 6.4–7.3 in dorsal-fin length. Dorsal-fin rays 15–16; anal-fin rays 13; pectoral-fin rays 26–28 (rarely 28); principle caudal-fin rays 12; total caudal-fin rays 20.

Description. Count and proportion for holotype given in parentheses; data for each examined specimen are presented in Table 1 . Dorsal-fin rays 15–16 (15); anal-fin rays 13 (13); pectoral-fin rays 26–27 (28); principle caudal-fin rays 12 (12); total caudal-fin rays 20 (20); gill rakers on second gill arch 8 (8); pre-anal vertebrae 21 (21); total vertebrae 34 (34).

Body slender, compressed posteriorly, anterior portion being flattened dorsally; body depth 6.9–8.1 (6.9) in SL, body width 5.9–7.6 (6.4) in SL, body narrower in smaller specimens. Caudal peduncle very short, depth 0.5– 0.6 (0.6) in its length. Head narrow and depressed, its length 2.8–3.2 (2.9) in SL, its width 5.4–6.2 (5.2) in SL.

Snout relatively long, giving specimen a “pointed” appearance in lateral view, but rounded in dorsal outline, its length 2.8–4.0 (3.2) in HL, snout shorter in smaller specimens. Mouth slightly inferior, oblique, and moderately large, but not extending below anterior margin of eye, upper-jaw length 3.1–4.3 (4.1) in HL. A single row of teeth on each jaw, those on lower jaw exclusively conical in shape, and those on upper jaw are compressed and have reversed tips. Upper edge of eye slightly protruding above dorsal profile of head, eye diameter 5.0–6.4 (5.7) in HL; interorbital space moderately broad, flat, distance 3.3–5.3 (3.9) in HL, interorbital broader in larger specimens. Anterior nostril lacking dermal flap; posterior nostril located slightly behind anterior edge of orbit and contains pronounced dermal flap.

Upper attachment of gill membrane opposite ninth pectoral-fin ray. Both dorsal and anal fins joined to caudal fin by a thin membrane. Dorsal-fin origin behind vertical at anus and forward to anal-fin origin, predorsal length 1.4–1.7 (1.5) in SL. Postdorsal-caudal distance 6.4–7.3 in dorsal-fin length. Dorsal-caudal distance when brought forward reaches about middle of pectoral fin. Disc single and small, its length 6.6–7.6 (6.3) in SL. Disc region A with 1–2 rows of flattened papillae, disc region B with 8 rows of flattened papillae. Anus closer to anal fin than to disc, about two-thirds distance from rear margin of disc to origin of anal fin.

Cephalic pores systems ( Fig. 3 ): There are 2 pores in nasal canal, 2 pores in postorbital canal, 2 pores in lachrymal canal, and 3 pores in preopercular canal.

Coloration in life ( Figs. 4 A–B) generally reddish brown with small black flecks irregularly spaced on body and a distinct dark (black to brown) stripe running from tip of snout, through eye, and terminating about half the distance from rear margin of orbit to gill opening. Some individuals with a pale streak originating on tip of both jaws, running over head between the eyes, and terminating just posterior to them. Base of pectoral fin darker than body color, but not as dark as stripe running through eye. Pupil dark with a distinct yellow ring on its outer margin. Median fins dark with light margins. In preservative, all color fades and specimens are uniformly tan.

Distribution. Lepadichthys erythraeus is presently known only from the Red Sea, from the Gulf of Aqaba and Gulf of Suez, south to Al Wajh (northeastern Saudi Arabia).

Remarks. A specimen of Lepadichthys erythraeus (BPBM 40985) was collected by the second author in 2008 and is the first specimen of this species to be photographed in color ( Fig. 4 C). The specimen was collected from the base of a coral block (about 1.5 m in diameter) on a reef flat with mixed sand and flat rock with patches of dead corals. The specimen was collected from within this live coral head in a depth of about 1 m in the sheltered Mangrove Bay (El Quseir, Egypt). Later, in 2011 one specimen was collected by the second author from Sharm el Moya area (Sharm el Sheikh, Egypt) from a fringing reef at a depth of 1–3 m and three specimens were collected at the entrance of Sharm el Moya Bay ( Egypt) from an isolated coral block. All collected specimens were in close association with sea urchins of the genus Diadema , utilizing the long spines for shelter. During recent field work in Saudi Arabia in June of 2013 additional specimens were collected by the second author in the northern part of the Red Sea (Maqna, Al Khuraybah, and Al Wajh). There are several lots in USNM collected by V. G. Springer and team in the Gulf of Aqaba and Gulf of Suez in 1969, we examined one lot (USNM 314225) from the Gulf of Aqaba that contains 14 specimens.

We noted two characters in our examination that differed from those reported in the original description, the first being the number of dorsal-fin rays. Briggs & Link (1963) did not use x-rays to count these elements (J. Briggs, pers. comm.), and this difference is readily explained by the difficulty in accurately counting the smallest of these rays, particularly at the origin of the dorsal fin. Second, the position of the anus was described as being “much closer” to the origin of the anal fin than to the rear margin of the disc. This subjective term makes interpretation difficult, and we herein report a semi-quantitative measure for the position of the anus as roughly two-thirds the distance from the anterior edge of the disc to the origin of the anal fin.

The position and number of the sensory head pores in L. erythraeus matches well with other known species of Lepadichthys ( Shiogaki & Dotsu 1983) . We thus agree with Shiogaki & Dotsu (1983) that these canals may be well suited to identify clingfish genera.

Lepadichthys erythraeus superficially resembles L. coccinotaenia Regan 1921 known from the Indian Ocean. Both species possess a dark band extending from the snout, through the eye, and terminating on the operculum. Lepadichthys erythraeus has more dorsal-fin and anal-fin rays, 15–16 and 13, respectively vs. 11–13 and 9–11 in L. coccinotaenia ; the dorsal and anal fins joined with the caudal by a thin membrane vs. not joined in L. coccinotaenia ; the postdorsal-caudal distance is shorter, 6.4–7.3 in dorsal-fin length vs. 2.7–2.8 in dorsal-fin length in L. coccinotaenia ; and the caudal peduncle is shorter, 0.5–0.6 in its length vs. 0.7–0.8 in its length in L. coccinotaenia . Lepadichthys erythraeus is also similar in morphology to L. sandaracatus known from Western Australia, but L. erythraeus has the upper attachment of the gill membrane opposite the ninth pectoral-fin ray vs. opposite the fourth to seventh pectoral-fin ray in L. sandaracatus ; and shorter postdorsal-caudal distance, 6.4–7.3 in dorsal-fin length vs. 3.4–3.8 in dorsal-fin length in L. sandaracatus .

Only one congeneric species occurs in the Red Sea, L. lineatus , which clearly differs from L. erythraeus by its striped color pattern and close association with crinoids. Some authors have placed this species in the genus Discotrema , but Briggs (2001) and Craig & Randall (2008) retain it in Lepadichthys .

Material examined. SMF 5586, holotype, 36.6 mm, Egypt, Hurghada (Al-Ghardaqa); USNM 314225, 28.5 mm, Israel, El Himeira, 19 July 1969; BPBM 40985, 19.1 mm, Egypt, El Quseir, 12 June 2008; uncatalogued, 1, 23.5 mm, Egypt, Sharm el Moya, 25 June 2011; uncatalogued, 3, 33.0–42.0 mm, Egypt, Sharm el Moya Bay, 13 July 2011; SMF 35410, 2, 26.6–36.0 mm, Saudi Arabia, south of Al Wajh, 14 June 2013; SMF 35411, 1, 37.9 mm, Saudi Arabia, Al Khuraybah, 24 June 2013; KAUMM 318, 2, 25.9–36.2 mm, Saudi Arabia, south of Al Wajh, 14 June 2013; KAUMM 319, 1, 35.3 mm, Saudi Arabia, Al Khuraybah, 24 June 2013.

Figures

FIGURE 2 Lepadichthys erythraeus, SMF 5586, holotype, 36.6 mm SL, Ghardaqa, Egypt. Photo by S. Traenkner.

FIGURE 3. Sensory head pores of Lepadichthys erythraeus. LC = Lachrymal canal pores, NC = Nasal canal pores, PO = Postocular canal pores, PR = Preopercular canal pores. In L. erythraeus there are 3 PR pores; the third is visible only on the ventral surface and cannot be seen in profile.

FIGURE 4. Lepadichthys erythraeus. A: uncatalogued, 23.5 mm SL, Sharm el Moya, Egypt, Red Sea; B: uncatalogued, 36 mm SL, Sharm el Moya Bay, Egypt, Red Sea. C: BPBM 40985, 19.1 mm SL, El Quseir, Egypt, Red Sea. Photos by S. V. Bogorodsky.