Gouania adriatica, 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 : 70-72

3.1.2 | Gouania adriatica sp. nov.

English name: Adriatic blunt-snouted clingfish

ZooBank LSID: urn:lsid:zoobank.org:act:F054E7C9-604F-41DA-8068-145DDCCC1FBE

Holotype. PMR VP4618 , male, 41.41 + 6.77 mm, Stoja, Pula, Croatia, 44 51 0 38.4 00 N, 13 49 0 05.0 00 E, coll. M. Wagner, July 17, 2016 (Figure 3).

Paratypes. ZSM-PIS-047650, male, 41.03 + 5.89 mm Envi beach, Vlorë, Albania, 40 23 0 16.3 00 N, 19 28 0 58.2 00 E, coll. M. Wagner, August 14, 2019 ; ZSM-PIS-047652, male, 27.3 + 4.27 mm, Trstenik Pelješac , Croatia, 42 54 0 07.7 00 N, 17 25 0 47.0 00 E, coll. M. Wagner, August 18, 2019 ; ZSM-PIS-047651, male, 34.53 + 5.65 mm, Stara Baška , Krk, Croatia, 44 56 0 45.3 00 N, 14 42 0 22.2 00 E, coll. M. Wagner, September 16, 2019 ; PMR VP3523 , juvenile of unidentified sex, 22.95 + 3.6 mm, Glavotok , Krk, Croatia, 45 05 0 44.9 00 N, 14 26 0 32.4 00 E, coll. M. Wagner, May 13, 2015 ; PMR VP3524 , male. 26.19 mm, caudal fin damaged and PMR VP3525 , female, 28.4 + 4.23 mm, both from Glavotok , Krk, Croatia, 45 05 0 44.9 00 N, 14 26 0 32.4 00 E, coll. M. Wagner, May 15, 2015 ; ZSM-PIS-047653, female, 34.42 + 4.85 mm and ZSM-PIS-047653, female, 35.23 + 4.9 mm, both from Pecine , Rijeka, Croatia, 45 18 0 52.4 00 N, 14 28 0 11.7 00 E, coll. M. Wagner, July 12, 2019 ; PMR VP4580 , female, 34.7 + 4.99 mm, Sv. Marina , Istria, Croatia, 45 01 0 42.1 00 N, 14 09 0 17.4 00 E, coll. M. Wagner, July 18, 2015 .

Diagnosis. Gouania adriatica 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 posterior edge of anterior nostril and a vertical line drawn through anterior edge of eye; (3) pointed upper and rounded lower posterior opercular edge; (4) longitudinal infralateral and suborbital transversal rows of superficial neuromasts placed in the well-defined deep groove; (5) body cross-section behind pectoral fin base half oval with straight ventral side; (6) the granules on body shallow and inconspicuous; (7) upper attachment of gill membrane opposite to 5th to 6th pectoral ray; (8) principal caudal-fin rays 12 – 13; (9) vertical eye diameter 3.4 – 4.3% of standard length; (10) horizontal eye diameter 3.0 – 3.7% of standard length; (11) head length 26.2 – 30.0% of standard length; (12) pectoral-fin length 8.7 – 11.3% of standard length; (13) prepectoral distance 25.1 – 28.5% of standard length; (14) ventral adhesive disc length 15.9 – 20.1% of standard length; (15) caudal-fin length 13.9% – 16.4 of standard length; (16) low number of vertebrae (= 35); (17) pharyngeal jaws with ceratobranchial 5 small, having several (about 5) small, conical teeth; (18) nasal bones club-shaped; (19) star-like pigmentation around eyes, reduced body pigmentation with no visible stripes.

Description. General morphology: Body proportions are given in Table 1. Body slender and elongated, posteriorly laterally compressed, body depth at pectoral fins 6.4 – 8.9 in SL, body depth at anus 7.7 – 10.2 in SL, body depth in width at pectoral fins 1.1 – 1.4, body depth in width at anus 0.7 – 0.8. Body cross-section behind pectoral fin base half oval with straight ventral side. Granules on body shallow and inconspicuous, making skin surface more dotted than granulose. Head dorsoventrally compressed, head depth in width at orbit 1.5 – 1.8, and moderately large, head length 3.3 – 3.8 in SL, head wider than body width maximum, head width at anterior sucking disc edge 0.7 – 0.9 in body width at pectoral fins. Dorsal head profile a straight line from nape above eye to upper lip tip. Head rounded in dorsal view. Snout large compared to eyes, preorbital distance 2.9 – 3.7 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, 7.3 – 9.5 in head length, vertical diameter of the eye 0.8 – 1.1 in horizontal eye diameter. Infraorbital invagination vertical to posterior part of eye or to mideye. Interorbital distance wide, 0.3 – 0.6 in horizontal eye diameter. Centre of eye much closer to tip of snout than to posterior margin of operculum, preorbital distance in postorbital distance 1.8 – 2.2. Anterior and posterior nostrils long tubes of about equal length. Nostrils well separated and posterior nostril located behind and dorsally to the anterior edge of eyes. Single large lobe at the posterior margin of anterior nostril or bilobed, longer than nostril. Posterior nostril rim 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 anterolateral 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, LIR 24 – 27, STR 1 – 3, POR 3 – 4, PTR 2, SLR 4 – 5, MR 9 – 11, AVR 2, PVR 1, ADR 2, PDR 1, HR 3, SR1 3, SR2 2, DLR 6 – 8, VLR 10 – 12. STR and LIR rows of superficial neuromasts placed in a well-defined deep groove. DLR row of superficial neuromasts anteriorly starts above pectoral fin, continuous dorsolateral and ends posteriorly downwards at midlateral level above anus or behind it. VLR anteriorly starts behind pectoral fin base, continuous ventrolateral and ends posteriorly upwards with last papilla nearly at midlateral level at caudal fin base. 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 posterior edge of anterior nostril and vertical line drawn through anterior edge of eye. Chin with bilobed or slightly bilobed fold at anterior edge covering MR row of superficial neuromasts. Gill membrane attached to isthmus, gill opening starting at the base of pectoral fin, with upper attachment of gill membrane opposite to 5th to 6th pectoral ray. Pointed upper and rounded lower posterior opercular edge. No subopercular spine. No fleshy pad present on lower pectoral base. Urogenital papilla present. Preanus length in postanus length 0.6 – 0.7. Anal papillae absent, area around anus only wrinkled.

Fins. Rudimentary dorsal and anal fins located well posteriorly and short, reduced to low ridges with very weak rays, connected to caudal fin. Pectoral rays 15 – 17. Caudal fin rounded, principal caudal rays 12 – 13. Ventral adhesive disc (Figure 4a) of “ double ” type, anterior margin crenate with large invagination on each lateral side and in some specimen central invagination at midventral visible; posterior margin crenate or villous. Disc small, disc length 5.0 – 6.3 in SL, its width slightly larger than its length, width in length 0.9 – 1.0. No papillae in region A and flattened papillae in regions B and C. In region B one or two rows of papillae with total papillae count 10 – 30 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 15th – 17th pectoral ray, i.e., at the ultimate or penultimate ray. In males, parts of disc region A appear to be perfused (see Figure 3, ventral view).

Colouration. Background colouration in life flesh-coloured to yellow, slightly transparent and head pigmentation prominent, with a star-like pattern around eyes (Figure 3). Body without (especially in juveniles) or with irregular melanocytes that are decreasing in density towards the posterior part of body or dotted (e.g., specimens from Vlorë) in life. Formaldehyde fixed specimens white to yellow and without pigments. In ethanol yellow or skin-coloured with pigments still present. For more pictures of life colouration see Supporting Information File S1.

Dentition and osteology. Upper jaw with outer row of about eight (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 five teeth, becoming narrowed to a single row of teeth laterally. Outer row continues laterally as two large caniniforms, followed behind by four or five medium-sized caniniforms. Lower jaw with outer row of about 15 (one side) medium-sized caniniforms frontally. Behind them single broad patch of small conical inner teeth medially wide about 5 – 6 teeth, becoming narrowed to a single row of teeth laterally. The single row of about eight larger caniniforms continuous laterally. Pharyngeal jaws with small ceratobranchial 5, having several (about 5) small, conical teeth (Figure 5a), pharyngobranchial 3 toothplate not visible on 3D models from microCT images. Number of vertebrae 35, abdominal 15 and caudal 20. 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. Maxillary, premaxillary, nasal and ceratobranchial 5 bones shaped as in Figure 5a. Nasal bones club-shaped.

Etymology. Named adriatica, meaning belonging to the Adriatic Sea, “ Mare Adriaticum ” or “ Mare Hadriaticum ” in Latin, which is the type locality of this species. The name is an adjective in the nominative singular (Article 11.9.1.1., ICZN, 1999).

Ecology and geographical distribution (Figure 1a). The geographic distribution ranges from the northern Adriatic Sea to the northern Ionian Sea (Island Corfu). In the Adriatic basin, the species is broadly sympatric with G. pigra . Quantitative data on ecology is largely lacking. At one site in the Adriatic basin (Pelješac) it was found not just in sympatry, but even syntopy, also with G. hofrichteri sp. nov., i.e., with both species in the same habitat (Figure 1c). Fish were found in the intertidal and sometimes syntopic with Lepadogaster lepagaster . During extreme low tide (late winter and early spring tides are the most extreme) this species was also found in layers of pebbles above the waterline.

Remarks. Gouania adriatica sp. nov. differs from slender-bodied Gouania species ( G. pigra and G. hofrichteri sp. nov.) by a dorsal head profile forming 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 in slender-bodied Gouania species), by a low number of vertebrae (Supporting Information Table S2; 35 vs. 38 – 40) and in life a star-like pigmentation around eyes (vs. no star-like pigmentation around eyes). Ten morphometric characters, as percentages of standard length, of G. adriatica sp. nov are nonoverlapping in range with both slender-bodied Gouania : head length, head width at head invagination, vertical and horizontal eye diameter, body width at pectoral fins, pectoral-fin length, prepectoral distance, ventral adhesive disc length, predisc length and caudal-fin length (values in the Table 1). There are also morphometric characters nonoverlapping in range with only one of the two slender-bodied Gouania (Table 1). In addition, G. adriatica sp. nov. differs from G. pigra by the posterior angle of jaws extending to between a vertical line drawn through the posterior edge of the anterior nostril and a vertical line drawn through the anterior edge of the eye (vs. posterior angle of jaws extending to, or close to, a vertical line drawn through the anterior edge of the anterior nostril) and principal caudal-fin rays 12 – 13 (vs. principal caudal rays 10 – 11). G. adriatica sp. nov. also differs from G. hofrichteri sp. nov. by longitudinal infralateral and suborbital transversal rows of superficial neuromasts placed in a 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. body cross-section behind pectoral fin base triangular with ventral flat and dorsal pointed), upper attachment of gill membrane opposite to 5th to 6th pectoral ray (vs. opposite to 3rd – 4th pectoral ray), the granules on body shallow and inconspicuous (vs. granules on body, at least on posterior part and nape, large and prominent). G. adriatica sp. nov. differs from other stout-bodied species ( G. orientalis sp. nov. and G. willdenowi ) by a posterior opercular edge with pointed upper tip and rounded lower edge (vs. posterior opercular edge w-shaped with two equally long tips) and a reduced pigmentation. In addition, it differs from G. orientalis sp. nov. by principal caudal-fin rays 12 – 13 (vs. principal caudal rays 10 – 11) and from G. willdenowi by vertical eye diameter 3.4 – 4.3% and horizontal eye diameter 3.0 – 3.7% of standard length (vs. vertical eye diameter 2.6 – 3.3% and horizontal eye diameter 2.3 – 2.9% of standard length). G. adriatica sp. nov. is known from the Adriatic Sea as well as Corfu island and has no overlapping geographic records with G. orientalis sp. nov. and G. willdenowi .