Gouania willdenowi ( Risso 1810 )

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 : 80-82

3.1.6 | Gouania willdenowi ( Risso 1810)

English name: Blunt-snouted clingfish

Neotype. PMR VP4574 , male, 46.11 + 6.56 mm, Cagnes-sur-mer, Nice, France, 43 39 0 22.1 00 N, 7 10 0 25.3 00 E, coll. M. Wagner, October 9, 2016 (Figure 9).

Additional material examined. PMR VP4568 , female, 36.2 + 5.18 mm , PMR VP4569 , female, 33.65 + 4.93 mm and PMR VP4570 , male, 31.13 + 4.36 mm, all from Banyuls-sur-mer, France, 42 29 0 18.6 00 N, 3 07 0 43.9 00 E, coll. M. Wagner, October 11, 2016 ; ZSM-PIS-047654, female, 40.03 + 5.41 mm, Cagnes-sur-mer, Nice , France, 43 39 0 22.1 00 N, 7 10 0 25.3 00 E, coll. M. Wagner, October 9, 2016 ; PMR VP4575 , male, 42.34 + 6.01 mm , PMR VP4576 , female, 40.5 + 5.58 mm and ZSM-PIS-047655, male, 28.42 + 5.94 mm, all from Cagnes-sur-mer, Nice , France, 43 39 0 22.1 00 N, 7 10 0 25.3 00 E, coll. M. Wagner, October 10, 2016 ; PMR VP4577 , female, 39.59 + 5.63 mm and PMR VP4578 , female, 36.82 + 5.4 mm, both from Le Port d'Alon, Toulon , France, 43 08 0 47.8 00 N, 5 42 0 27.2 00 E, coll. M. Wagner, October 16, 2016 .

Synonyms. Lepadogaster willdenowi Risso, 1810: 75 (original description; type locality: Nice; holotype: unknown); Rupisuga nicensis Swainson 1839: 339 (original description; type locality: Nice?; holotype: unknown), Lepadogaster latirostris Costa 1850: 4 (original description; type locality: Naples; holotype: unknown); Leptopterygius wildenowi Troschel, 1860: 206 (original description; type locality: Nice; holotype: unknown); Leptopterygius coccoi Troschel, 1860: 207 (original description; type locality: Messina; holotype: unknown).

Diagnosis. Gouania willdenowi differs from congeneric species by the combination of the following characters: (1) dorsal head profile straight between nape above eye and upper lip tip; (2) posterior angle of jaws extends 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; (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) vertical eye diameter 2.6 – 3.3% of standard length; (9) horizontal eye diameter 2.3 – 2.9% of standard length; (10) head length 24.3 – 28.8% of standard length; (11) pectoral-fin length 8.6 – 9.3% of standard length; (12) prepectoral distance 24.4 – 28.4% of standard length; (13) ventral adhesive disc length 17.1 – 19.3% of standard length; (14) caudal-fin length 13.5 – 15.5% of standard length; (15) moderate number of vertebrae for the genus (Supporting Information Table S2; 37 – 38); (16) pharyngeal jaws with small ceratobranchial 5, having several small conical teeth; (17) nasal bones club-shaped; (18) star-like pigmentation around eyes, in life body colouration dark with clear stripes visible in less pigmented specimens; (19) distribution range restricted to the western Mediterranean.

Description. General morphology: Body proportions are given in Table 1. Body slender and elongated, posteriorly laterally compressed, body depth at pectoral fins 7.5 – 8.8 in SL, body depth at anus 8.8 – 11.4 in SL, body depth in width at pectoral fins 1.1 – 1.3, body depth in width at anus 0.8 – 0.9. Body 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 – 4.1 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 2.8 – 3.5 in head length, 0.3 in horizontal eye diameter. Snout wide, not produced, blunt. Internostril space gently convex. Eyes dorsolateral, with lower eye edge rounded. Eyes small, 9.1 – 11.0 in head length, vertical diameter of the eye 0.8 – 1.0 in horizontal eye diameter. Infraorbital invagination vertical to posterior part of eye. Interorbital distance wide, 0.3 – 0.4 in horizontal eye diameter. Centre of eye much closer to tip of snout than to posterior margin of operculum, preorbital distance in postorbital distance 1.7 – 2.3. 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 dermal flap of leaf shape at the posterior margin of anterior nostril, longer than nostril. Posterior nostril rim crenate with no extension. Skin with small granules. 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, LIR 24 – 28, STR 3 – 4, POR 3 – 4, PTR 2 – 3, SLR 5 – 6, MR 10 – 11, AVR 2, PVR 1, ADR 2 – 3, PDR 0 – 1, HR 3 – 4, SR1 3 – 4, SR2 1 – 2, DLR 6 – 9, VLR 11 – 14. 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 above anus. VLR anteriorly starts behindpectoral fin base, continuous ventrolaterally and ends posteriorly upwards with last papilla nearly at midlateral level at caudal-fin base. Mouth terminal, upper and lower lips ends 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 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 4th – 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 0.7 – 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 16 – 19. Caudal fin rounded, principal caudal rays 11 – 12. Ventral adhesive disc (Figure 4e) of “ double ” type, anterior margin crenate with large invagination on each lateral side; posterior margin crenate. Disc small, disc length 5.2 – 5.9 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 two rows of papillae with total papillae count 17 – 28 and in region C two rows of papillae with total papillae count 9 – 14. 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 – 18th pectoral ray, i.e., penultimate ray. Males can have two prominent seemingly perfused finger-like extensions on each site of sucking disc that sometimes equal or exceed length of disc region A (Figure 4f) ( Hofrichter, 1995; Hofrichter & Patzner, 2000).

Colouration. Background colouration of live specimens flesh-coloured, orange or yellow (Figure 9) and star-like pigmentation around eyes present. In life body coloration with dark clear stripes visible in less pigmented specimens (e.g., Messina), other specimens with irregular marbled pattern. Formaldehyde fixed specimens white-yellow and without pigments. Ethanol fixed specimens white to skin coloured, striped pigmentation visible. For more pictures of life colouration see Supporting Information File S1.

Dentition and osteology. Upper jaw with outer row four (one side) medium-sized caniniforms frontally, two median teeth larger. Behind them inner small conical teeth irregularly scattered in two separate (left and right) droplike patches medially wide about 4 – 5 teeth, becoming narrowed to a single row of teeth laterally. Outer row continues laterally as single large caniniform, followed behind by three medium-sized caniniforms. Lower jaw with outer row of eight – 10 (one side) medium-sized caniniforms frontally. Behind them single broad patch of small conical inner teeth medially wide about 3 – 4 teeth, becoming narrowed to a single row of teeth laterally. The single row of four larger caniniforms continuous laterally. Pharyngeal jaws with small ceratobranchial 5 having several (6 – 7) small conical teeth (Figure 5e), pharyngobranchial 3 toothplate not visible on 3D models from microcomputed tomography (microCT) images. Number of vertebrae 37 – 38, abdominal 16 and caudal 21 – 22 (Supporting Information Table S2). The first gill arch with hemibranch, the 2nd – 4th gill arches with holobranchs. Subopercle indistinguishable from opercle, shaped as its posterior elongated extension, not forming or having subopercular spine. Six branchiostegals. Club-shaped nasal bones. Maxillary, premaxillary, nasal and ceratobranchial 5 bones shaped as on Figure 5e.

Etymology. Risso (1810) formed the name from a personal name, as the noun in the genitive case, with “ i ” added to the stem of the name (presently under Article 31.1.2., ICZN, 1999). We followed the spelling of the species as recommended by Fricke et al. (2020b), “ G. willdenowi ”. In the text of the original description it appeared as “ 4. L. Willdenow. N. L. Willdenowi ”. So we concluded that “ Wildenowii” in the index represents a case of misspelling ( Risso, 1810). We think that the name was given in honour of Carl Ludwig Willdenow, even though this is not explicitely stated in Risso (1810). Hence, “ L. willdenowi ” would be the correct spelling of the name.

Ecology and geographical distribution (Figure 1a). The distribution range of G. willdenowi is restricted to the western Mediterranean basin with an easternmost record from Messina (Sicily). The species reaches highest abundances in pebble and boulder beaches of less than 0.5 m depth (24 individuals/m 2 in Messina), but can be found down to 2 m of water depth ( Hofrichter & Patzner, 2000; Patzner, 1999). Gouania willdenowi can be sometimes found in sympatry with Lepadogaster lepadogaster and males build and guard nests under boulders during spawning season ( Hofrichter, 1995; own observations).

Remarks. Gouania willdenowi differs from known congeners by various characters among which the most useful were selected for diagnosis and are elaborated on here. Some of the characters differing among (some) species and that are not used in the species diagnosis are nonetheless mentioned here as they are interesting for comparison. G. willdenowi differs from slender-bodied Gouania species ( G. pigra and G. hofrichteri sp. nov.) by a straight dorsal head profile between nape above eye and upper lip tip (vs. dorsal head profile in lateral view “ S ” curved, concave above eye and convex at nape), infraorbital invagination vertical to posterior part of eye (vs. infraorbital invagination below anterior half of eye or below mideye) and a star-like pigmentation around eyes (vs. no pigmentation around eyes). Eleven morphometric characters as percentages of standard length of G. willdenowi are nonoverlapping in range with both slender-bodied Gouania : head length, all three head width measures, preorbital distance, 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 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. willdenowi differs from G. pigra by a posterior angle of jaws which extending to between vertical line drawn through posterior edge of anterior nostril and vertical line drawn through anterior edge of eye (vs. posterior angle of jaws extending at, or close to, vertical line drawn through anterior edge of anterior nostril). G. willdenowi also differs from G. hofrichteri sp. nov. by posterior opercular edge w-shaped with two equally long tips (vs. posterior opercular edge with pointed upper tip and rounded lower 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) and the granules on body shallow and inconspicuous (vs. granules on body, at least on posterior part and nape, large and prominent). G. willdenowi differs from the stout-bodied species G. adriatica sp. nov. by posterior opercular edge w-shaped with two equally long tips (vs. posterior opercular edge with pointed upper tip and rounded lower edge) and by vertical eye diameter 2.6 – 3.3% and horizontal eye diameter 2.3 – 2.9% of standard length (vs. vertical eye diameter 3.4 – 4.3% and horizontal eye diameter 3.0 – 3.7% of standard length). G. willdenowi has no nonoverlapping external morphological differences to G. orientalis sp. nov. but differs by its larger number of vertebrae (Supporting Information Table S2; 37 – 38 vs. 35 – 36). G. willdenowi is only known from the Western Mediterranean and has nonoverlapping geographic distribution with all other Gouania species. Based on the distributional data presented here, morphological and genetic data as well as the taxonomic positioning of the species G. willdenowi (see Discussion, Taxonomical and systematic considerations below) and the fact that no original types (holo-, lectotypes) exist we designate a neotype for this species. The designated neotype was collected close to the original locus typicus (Nice, France) and is accessible as the voucher number PMR VP 4574 at the PMR.

Neotype designation. We designated a neotype for G. willdenowi , fulfilling the qualifying conditions (Article 75.3, ICZN, 1999). We are positive that no name-bearing type specimens exist for G. willdenowi ( Fricke et al., 2020b; Article 75.3.4, ICZN, 1999). The genus Gouania represents a complex zoological problem (Article 75.2, ICZN, 1999) of morphologically very similar congenerics. The redescription of G. willdenowi , resurrection of G. pigra and description of three new species of Gouania in the hitherto monotypic genus thus represented an exceptional need for designation of a neotype for G. willdenowi (Article 75.3, ICZN, 1999). The situation could become even more complicated if more Gouania linages were to be found around the Mediterranean, which is not at all unlikely. In that case, the name-bearing material of the present species, holotypes and neotypes, should be available for comparison with potential new material. The diagnostic characters are stated in the species redescription (Article 75.3.1, ICZN, 1999), which is sufficient to ensure the recognition of the species (Article 75.3.3, ICZN, 1999). The neotype fits the original species descriptions of G. willdenowi ( Risso, 1810; Article 75.3.5, ICZN, 1999) and the neotype were collected close to the original type localities (Article 75.3.6, ICZN, 1999). The neotype is stored in a scientific museum collection (Article 75.3.7, ICZN, 1999).