Gouania orientalis, Wagner & Kovac & Koblmüller, 2021

Wagner, Maximilian, Kovac, Marcelo & Koblmüller, Stephan, 2021, Unravelling the taxonomy of an interstitial fish radiation: Three new species of Gouania (Teleostei: Gobiesocidae) from the Mediterranean Sea and redescriptions of G. willdenowi and G. pigra, Journal of Fish Biology 98 (1), pp. 64-88 : 72-75

3.1.3 | Gouania orientalis sp. nov.

English name: Oriental blunt-snouted clingfish

ZooBank LSID: urn:lsid:zoobank.org:act:4E02C972-6907-41E0-A2B7-0215FDB49319

Holotype. PMR VP4585 , male, 32.8 + 4.93 mm, Plakias, Crete, Greece, 35 11 0 40.8 00 N, 24 22 0 50.9 00 E, coll. M. Wagner, August 9, 2016 (Figure 6).

Paratypes. PMR VP4719 , male, 37.53 + 5.59 mm, Gulf of Corinth , Greece, 38 10 0 17.0 00 N, 22 16 0 26.7 00 E, coll. M. Wagner, August 23, 2018 ; PMR VP4584 , female, 26.0 + 4.56 mm, Plakias , Crete, Greece, 35 11 0 40.8 00 N, 24 22 0 50.9 00 E, coll. M. Wagner, August 9, 2016 ; ZSM-PIS-047658, female, 30.55 + 5.25 mm and PMR VP4588 , juvenile of unidentified sex, 17.92 + 2.98 mm, both from Vatos , Crete, Greece, 34 59 0 41.0 00 N, 25 33 0 17.3 00 E, coll. M. Wagner, August 13, 2016 ; ZSM-PIS-047659, female, 17.88 + 2.79 mm and PMR VP4596 , female, 17.09 + 2.69 mm, both from Souda Beach , Plakias, Crete, Greece, 35 11 0 32.1 00 N, 24 22 0 04.9 00 E, coll. M. Wagner, August 17, 2016 ; ZSM-PIS-047660, female, 24.87 + 3.56 mm and ZSM-PIS-047660, female, 23.68 + 3.39, mm, both from Chamolia , Greece, 37 54 0 58.5 00 N, 24 02 0 08.7 00 E, coll. M. Wagner, August 16, 2018 ; ZSM-PIS-047661, male, 28.52 + 4.04 mm, Feloti Beach , Kapsáli, Kythira, Greece, 36 09 0 16.2 00 N, 22 57 0 52.0 00 E, coll. M. Wagner, August 21, 2018 .

Diagnosis. Gouania orientalis sp. nov. differs from its congeners by the combination of the following characters: (1) dorsal head profile a straight line from nape above eye to upper lip tip; (2) posterior angle of jaws extends to between a vertical line drawn through anterior edge of eye and a vertical line drawn through anterior part of eye; (3) infraorbital invagination vertical to posterior part of eye; (4) posterior opercular edge w-shaped with two equally long tips; (5) longitudinal infralateral and suborbital transversal rows of superficial neuromasts placed in the well-defined deep groove; (6) trunk cross-section behind pectoral fin base half oval with straight ventral side; (7) granules on body shallow and inconspicuous; (8) upper attachment of gill membrane opposite to 5th to 6th pectoral ray; (9) pectoral rays 17 – 19; (10) upper attachment of disc membrane attaching to base of pectoral fin at 16th – 18th pectoral ray; (11) principal caudal rays 10 – 11; (12) head length 25.0 – 28.9% of standard length; (13) pectoral fin length 8.2 – 10.3% of standard length; (14) prepectoral distance 24.7 – 28.2% of standard length; (15) ventral adhesive disc length 14.9 – 19.0% of standard length; (16) caudal-fin length 14.2 – 17.5% of standard length; (17) low number of vertebrae (Supporting Information Table S2; 35 – 36) (18) pharyngeal jaws with small ceratobranchial 5, having a few hardly recognizable small conical teeth; (19) nasal bones with inconspicuous frontal end; (20) in life star-like pigmentation around eyes, body colouration dark, sometimes marbled or with stripes.

Description. General morphology: Body proportions are given in Table 1. Body slender and elongated, posteriorly laterally compressed, body depth at pectoral fins 6.9 – 8.6 in SL, body depth at anus 7.8 – 9.3 in SL, body depth in width at pectoral fins 1.1 – 1.2, body depth in width at anus 0.8 – 0.9. Trunk cross-section behind pectoral fin base half oval with straight ventral side. Granules on body shallow and inconspicuous. Head dorsoventrally compressed, head depth in width at orbit 1.5 – 1.9 and moderately large, head length 3.5 – 4.0 in SL, head wider than body width maximum, head width at anterior sucking disc edge 0.7 – 0.8 in body width at pectoral fins. Dorsal head profile straight between nape above eye and upper lip tip. Head rounded in dorsal view. Snout large compared to eyes, preorbital distance 3.1 – 3.8 in head length, 0.3 – 0.5 in horizontal eye diameter. Snout wide, not produced, blunt. Internostril space gently convex. Eyes dorsolateral, with lower eye edge rounded. Eyes small, 7.0 – 10.1 in head length, vertical diameter of the eye 0.8 – 1.1 in horizontal eye diameter. Infraorbital invagination vertical to posterior part of eye. Interorbital distance wide, 0.3 – 0.5 in horizontal eye diameter. Centre of eye much closer to tip of snout than to posterior margin of operculum, preorbital distance in postorbital distance 1.9 – 2.3. Anterior and posterior nostrils long tubes of about equal length. Nostrils well separated and posterior nostril located behind and dorsally to anterior edge of eyes. Single large dermal flap at the posterior margin of anterior nostril leaf shaped, longer than nostril. Posterior nostril rim slightly crenate with no extension. Head lateral line system with canals with pores and with superficial neuromasts arranged in rows. Head canals reduced and pores small. Single pore in nasal canal near posterior nostril. Single pore in postorbital canal close to posterior eye edge. Two pores in mandibular canal, anterior one close to anteriolateral angle of mouth, posterior pore slightly in front of vertical of posterior angle of jaws, posterior pore usually more prominent. Lachrymal as well as preopercular canals and pores absent. Rows of superficial neuromasts as follows: SR 2, NR 3 – 5, LIR 23 – 28, STR 3 – 4, POR 3 – 4, PTR 2, SLR 5, MR 9 – 13, AVR 2, PVR 1, ADR 1 – 3, PDR 1, HR 3, SR1 3, SR2 1 – 2, DLR 6 – 8, VLR 9 – 13. STR and LIR rows of superficial neuromasts placed in the well-defined deep groove. DLR row of superficial neuromasts anteriorly starts above pectoral fin, continuously dorsolateral and ends posteriorly downwards at midlateral level and variably, vertical to anus or in front of it or behind it. VLR anteriorly starts behind pectoral fin base, continuous ventrolaterally and ends posteriorly upwards with last papilla nearly at midlateral level at caudal fin base or close to it. Mouth terminal, upper and lower lips end about equally, lips fleshy, upper lip larger than the lower lip. Posterior angle of jaws extends to between vertical line drawn through anterior edge of eyes and vertical line drawn through anterior part of eye. Chin with bilobed or slightly bilobed fold at anterior edge covering MR row of superficial neuromasts. The gill membrane is attached to isthmus, gill opening starting at the base of pectoral fin, with the upper attachment of the gill membrane is opposite to 5th to 6th pectoral ray. Posterior opercular edge w-shaped with two equally long tips. No subopercular spine. No fleshy pad present on lower pectoral base. Urogenital papilla present. Preanus length in postanus length 0.6 – 0.8. Anal papillae absent, the area around anus wrinkled.

Fins. Rudimentary dorsal and anal fins located well posteriorly and short, reduced to low ridges with very weak rays, connected to the caudal fin. Pectoral rays 17 – 19. Caudal fin rounded, principal caudal rays 10 – 11. Ventral adhesive disc (Figure 4b) of “ double ” type, anterior margin crenate with large invagination on each lateral side and central invagination at midventral; posterior margin slightly crenate. Disc small, disc length 5.3 – 6.7 in SL, its width slightly larger than its length, width in length 0.9 – 1.1. No papillae in region A and flattened papillae in regions B and C. In region B two to three rows of papillae with total papillae count 21 – 37 and in region C two rows of papillae with total papillae count 9 – 15. No inner row of papillae on lateral sides of the central part of the anterior disc. Upper attachment of disc membrane attaching to base of pectoral fin at 16th – 18th pectoral ray (i.e., on penultimate ray).

Colouration. Background colour of live specimens bright yellow to brownish red (Figure 6) and prominent star-like pigmentation around eyes present. Body pigments reduced (juveniles) or, behind head, with clearly visible regular stripes (juveniles, e.g., Attica, Crete, Kythira) or marbled (i.e., irregular pattern; e.g., Gulf of Corinth). Specimens from Crete, Kythira and the Gulf of Corinth have stronger pigmentation (see Figure 6), hence, the pigmentation pattern can be less clearly visible. Formaldehyde fixed specimens white-yellow and without pigments. Ethanol fixed specimens white to skin-coloured, pigmentation present (also stripes). For more pictures of life colouration see Supporting Information File S1.

Dentition and osteology. Upper jaw with outer row of about 10 (one side) medium-sized caniniforms frontally. Behind them inner small conical teeth irregularly scattered in two separate (left and right) drop-like patches medially wide about 5 – 6 teeth, becoming narrowed to a single row of teeth laterally. Outer row continues laterally as two large caniniforms, followed behind by about eight medium-sized caniniforms. Lower jaw with outer row of about 10 (one side) medium-sized caniniforms frontally. Behind them single broad patch of small conical inner teeth wide medially about 5 – 6 teeth, becoming narrowed to a single row of teeth laterally. The single row of about six larger caniniforms continuous laterally. Pharyngeal jaws with small ceratobranchial 5, having a few (1 – 2) poorly recognizable small conical teeth (Figure 5b), pharyngobranchial 3 toothplate not visible on 3D models from microCT images. Number of vertebrae 35 – 36, abdominal 16 and caudal 21 (Supporting Information Table S2). The first gill arch with hemibranch, the 2nd to 4th gill arches with holobranchs. Subopercle indistinguishable from opercle, shaped as its posterior elongated extension, not forming or having subopercular spine. Six branchiostegals. Nasal bones with inconspicuous frontal end. Maxillary, premaxillary, nasal and ceratobranchial 5 bones shaped as on Figure 5b.

Etymology. Named orientalis , from the Latin word “ oriens ” for “ east ”, which describes the distribution range of the species that is restricted to the oriental Mediterranean basin. The name is an adjective in the nominative singular (Article 11.9.1.1., ICZN, 1999).

Ecology and geographical distribution (Figure 1a). The known species distribution range encompasses the Gulf of Corinth, the Aegean Sea (Attica) and on the islands Crete and Kythira. Quantitative data on ecology is largely lacking. Gouania orientalis sp. nov. occurs in sympatry or even syntopy with G. hofrichteri sp. nov. throughout its distribution range. The species inhabits intertidal and subtidal pebble and boulder beaches.

Remarks. Gouania orientalis sp. nov. differs from slender-bodied Gouania species ( G. pigra and G. hofrichteri sp. nov.) by a dorsal head profile that forms a straight line between nape above eye and upper lip tip (vs. dorsal head profile in lateral view “ S ” curved, concave above eye and convex at nape), an infraorbital invagination vertical to posterior part of eye (vs. infraorbital invagination below anterior half of eye or below mideye), lower number of vertebrae (Supporting Information Table S2; 35 – 36 vs. 38 – 40) and a star-like pigmentation around eyes (vs. no star-like pigmentation around eyes). Nine morphometric characters as percentages of standard length of G. orientalis sp. nov. are nonoverlapping in range with both slender-bodied Gouania : head length, horizontal eye diameter, body width at pectoral fins, pectoral-fin length, prepectoral distance, ventral adhesive disc length, distance between the posterior margin of sucking disc and anus, caudal base depth and caudal-fin length (values in Table 1). There are also morphometric characters nonoverlapping in range with only one of the two slender-bodied Gouania (Table 1). In addition, G. orientalis sp. nov. differs from G. pigra by a posterior angle of jaws extending to between vertical line drawn through anterior edge of eye and vertical line drawn through anterior part of eye (vs. posterior angle of jaws extending to, or close to, a vertical line drawn through the anterior edge of the anterior nostril), pectoral rays 17 – 19 (vs. pectoral rays 13 – 16) and upper attachment of disc membrane attaching to base of pectoral fin at 16th – 18th pectoral ray (vs. upper attachment of disc membrane attaching to base of pectoral fin at 12th – 15th pectoral ray). G. orientalis sp. nov. is also different from G. hofrichteri sp. nov. by posterior opercular edge w-shaped with two equally long tips (vs. pointed upper tip and rounded lower posterior opercular edge), longitudinal infralateral and suborbital transversal rows of superficial neuromasts placed in the well-defined deep groove (vs. longitudinal infralateral and suborbital transversal rows of superficial neuromasts placed in shallow groove disappearing in posterior part of longitudinal infralateral row), body cross-section behind pectoral fin base half oval with straight ventral side (vs. trunk cross-section behind pectoral fin base triangular with ventral flat and dorsal pointed), granules on body shallow and inconspicuous (vs. granules on body, at least on posterior part and nape, large and prominent) and upper attachment of gill membrane opposite to 5th – 6th pectoral ray (vs. the upper attachment of the gill membrane opposite to 3rd – 4th pectoral ray). G. orientalis sp. nov. differs from the stout-bodied species G. adriatica sp. nov. in posterior opercular edge w-shaped with two equally long tips (vs. posterior opercular edge with pointed upper tip and rounded lower edge), principal caudal rays 10 – 11 (vs. principal caudal-fin rays 12 – 13) and pattern of pigmentation (stripes, marbles vs. reduced pigmentation). G. orientalis sp. nov. has no nonoverlapping external morphological differences to G. willdenowi but differs by its low number of vertebrae (Supporting Information Table S2; 35 – 36 vs. 37 – 38). G. orientalis sp. nov. is known from Aegean and Ionian Sea and has nonoverlapping geographic distribution with G. adriatica sp. nov., G. pigra and G. willdenowi .