Key for the identification of Mediterranean marine gobies from photographs of live individuals

1a One dorsal fin; dorsal and anal fins confluent with caudal fin (Fig. 1).................................................................................................... Trypauchen vagina (Bloch & Schneider, 1801)

1b Two dorsal fins: if first dorsal fin reduced, then second dorsal fin and anal fin clearly separated from caudal fin....... 2

2a (1) Head and predorsal area completely covered with oval to rounded, clearly defined, dark to orange or yellow-orange spots or blotches (Fig. 2)................................................................................. 3

2b (1) Head and predorsal area without oval to rounded, clearly defined, dark or orange spots........................... 6

3a (2) Side of head with blue-edged dark reddish spots; dorsal half of body with 2 large green-edged black ocellated spots (Fig. 3)...................................................... Cryptocentrus caeruleopunctatus (Rüppell, 1830)

3b (2) No pale to bluish edge around head spots; no ocellated spots on body......................................... 4

4a (3) Head shorter than caudal fin; body slender; body with a mix of yellow and dark brown markings, first dorsal fin with yellow spots (Fig. 4).................................................... Vanderhorstia mertensi Klausewitz, 1974

4b (3) Head longer than caudal fin; body moderately deep; body with either orange or dark brown markings, first dorsal fin with orange or dark brown longitudinal bands............................................................... 5

5a (4) Body pale bluish gray, with pattern of large black, brown-purple or orange-brown blotches and spots (Fig. 5)........................................................................... Thorogobius ephippiatus (Lowe, 1839)

5b (4) Body pale, with orange to yellow-orange spots (Fig. 6).............. Thorogobius macrolepis (Kolombatović, 1891)

6a (2) Head and body are completely dark brown to purplish, with definite white markings, including 3–6 blotches at least as large as eye diameter on dorsal half of body, a white transverse band in predorsal area, and dorsal and caudal fins with a broad white outer edge (Fig. 7)................................................ Didogobius schlieweni Miller, 1993

6b (2) Head and body are not completely dark brown to purplish or if it is, then without conspicuous white blotches......... 7

7a (6) A well delineated dark area on body between second dorsal-fin base and anal-fin base, contrasting with a plain pale caudal peduncle (Fig. 8)....................................................... Lebetus guilleti (Le Danois, 1913)

7b (6) Color pattern without a dark area below second dorsal fin contrasting with pale caudal peduncle................... 8

8a (7) Two continuous or interrupted dark brown stripes on body, sometimes not well defined, the upper stripe running from above eyes along back and ending at upper caudal-fin base, the lower stripe running from snout tip through eyes along mid-body to caudal fin (Fig. 9)................................................ Tridentiger trigonocephalus (Gill, 1859)

8b (7) Color pattern with no or with a single longitudinal dark stripe............................................... 9

9a (8) Head and body pale to white, with one broad longitudinal dark stripe beginning from the upper lip, continuing over eye and above body midline, to caudal-fin base (Fig. 10).............................. Gobius vittatus Vinciguerra, 1883

9b (8) Color pattern without longitudinal dark stripe along body side, or if dark stripe is present, then body with other dark markings........................................................................................ 10

10a (9) Head and body red with irregular white markings, first dorsal fin entirely dark (Fig. 11)............................................................................... Lebetus patzneri Schliewen, Kovačić & Ordines, 2019

10b (9) Head and body coloration not red, or if the primary pattern is reddish, then the first dorsal fin is not entirely dark (although it can display a dark spot or blotch)................................................................... 11

11a (10) Body red with 5 whitish saddles on back, the first anterior at the origin of the first dorsal fin, the last on caudal peduncle just before caudal fin; 5–6 barely-defined white to yellowish blotches along ventral profile; in males, caudal fin and sometimes posterior body yellow, and dorsal fins yellowish with at least one oblique pink to light purple stripe on each fin (Fig. 12).......................................................... Speleogobius trigloides Zander & Jelinek, 1976

11b (10) Head and body not red or if the primary pattern is reddish, then dorsal and ventral whitish marks are either absent or there are more than 5 dorsal and 6 ventral whitish marks...................................................... 12

12a (11) Body brown to reddish or beige, head reddish; 3 dark bars on dorsal half of body alternating with 4 pale areas (Fig. 13), bars linked with 4 dark blotches on lower side, one more midlateral blotch on caudal peduncle (Fig. 13)............................................................... Speleogobius llorisi Kovačić, Ordines & Schliewen, 2016

12b (11) Head and body not red or brown-red, or if primary pattern is reddish, then there are more than 3 dark bars on dorsal half, alternating with more than 4 pale areas, and without 4 dark blotches on lower side............................. 13

13a (12) Body mostly dark brown with 3 narrow pale bars extending onto ventral half of body (the first just before first dorsal fin and extending onto pectoral-fin base), plus a very thin one on caudal-fin base (Fig. 14)...................................................................................... Didogobius splechtnai Ahnelt & Patzner, 1995

13b (12) Body not mostly dark brown or, if mostly dark brown, then without well-defined transverse pattern of 3 pale bars extending onto ventral half of body........................................................................... 14

14a (13) Body mostly mottled brown with midlateral row of broad rectangular ill-defined dark blotches; thin whitish saddles on back (three below second dorsal fin); side of lips vermillion with prominent white bar on lips at angle of mouth (red color usually not detectable under natural light) (Fig. 15)................................... Gobius cruentatus Gmelin, 1789

14b (13) Head and body usually without mottled brown pattern and midlateral brown blotches, if mottled brown pattern present, then lips not orange or red.............................................................................. 15

15a (14) Head and body pale to grayish background often with a bluish hue, 3–4 slightly oblique yellow to yellow-orange stripes on side of head, and one slanting yellow stripe above them behind eye (Fig. 16)........................................................................................................ Lesueurigobius suerii (Risso, 1810)

15b (14) Head without oblique yellow to yellow-orange stripes.................................................... 16

16a (15) Body with two longitudinal rows of brownish spots (often with yellow to orange hue), one row along back and another along lateral midline; second dorsal fin with a yellow to orange outer margin and whitish to blue submarginal band; both dorsal fins and upper half of caudal fin with yellow to orange spots (Fig. 17)...... Lesueurigobius friesii (Malm, 1874)

16b (15) Body without longitudinal rows of gray-brown or orange-brown spots, or if such rows are present, then second dorsal fin without a combination of yellow margin and whitish to blue submarginal band................................ 17

17a (16) Head and body with irregular orange blotches arranged in longitudinal series; two horizontal irregular orange stripes on head, one behind eye, the other from below eye to upper pectoral-fin base; V-shaped orange stripe across snout; first dorsal fin with blackish oval blotch between third and fifth spines (sometimes faint) (Fig. 18)....................................................................................... Gobius kolombatovici Kovačić & Miller, 2000

17b (16) Head and body without orange blotches, or if orange blotches present, then no orange V-shaped line on snout, or if V-shaped line is present, then no horizontal stripe present behind eye; dark blotch on first dorsal fin absent, or if present blotch is elongate and extends along fin base, usually from first to fifth spine......................................... 18

18a (17) Head and body grayish with pale orange, reddish, rarely with pinkish blotches and speckles, or indistinct bars of these colors on paler background; a series of short pearly white bars arranged in 3-5 pairs along lower body; anterior nostrils contrastingly white (Fig. 19)......................................... Vanneaugobius dollfusi Brownell, 1978

18b (17) No pure orange markings, although overall color can be brown-orange, reddish or with traces of orange pigmentation... ............................................................................................... 19

19a (18) Body with pattern of transverse narrow pale bars on reddish to brownish background; 3 pale, uninterrupted bars radiating downwards from eye to ventral part of head, two bars below eye and one behind (Figs. 20–22).................... 20

19b (18) Body and head usually without transverse bars, or if pattern is transverse, then less than three complete pale bars radiating downwards from eye to the ventral part of head......................................................... 21

20a (19) Body reddish to orangish brown with 10–15 narrow bluish bars (Fig. 21)............................................................................................. Corcyrogobius liechtensteini (Kolombatović, 1891)

20b (19) Body brownish with 6–7 narrow pale bars (Fig. 22)............................ Gammogobius steinitzi Bath, 1971

21a (19) Head clearly depressed (distinctly dorsoventrally flattened) (Figs. 23, 24 and 25)............................... 22

21b (19) Head not clearly depressed (not distinctly dorsoventrally flattened).......................................... 23

22a (21) Body fawn to blackish with a broad pale to white predorsal bar extending ventrally on pectoral-fin base; no pale saddle at origin of first dorsal fin; prominent to indistinct white saddle at origin of second dorsal fin, sometimes another short saddle below posterior part of second dorsal fin; cheeks pigmented, densely dotted or with reticulate pattern (Fig. 24)................................................................ Chromogobius quadrivittatus (Steindachner, 1863)

22b (21) Broad, often faint pale bar on predorsal area, extending ventrally on pectoral-fin base; 5 or 6, often faint, pale saddles of same intensity, extending or not as lateral bars, the first at origin of first dorsal fin, the last just behind second dorsal fin; cheeks pale with two dark oblique bands radiating downwards from eye in the shape of an inverted V or a triangular mark (Fig. 25).................................................... Chromogobius zebratus (Kolombatović, 1891)

23a (21) Body pattern of pale transverse bars on reddish, brownish or greenish background, sometimes reduced to pale dorsal saddles, side of body then more or less uniform or mottled reddish, brownish or greenish (Figs. 26–29)............. 24

23b (21) No transverse bars on the body; if patterned with pale dorsal saddles, then pigmentation on body side not uniform or mottled......................................................................................... 26

24a (23) Head and body prevailing reddish or orangish with pale bars (Fig. 26a), or with a series of short white saddles along back and side of body more or less uniform (Fig. 26b); no midlateral row of small black spots; whitish spot at the upper edge of opercle.................................................. Odondebuenia balearica (Pellegrin & Fage, 1907)

24b (23) Head and body not reddish or orangish, usually with brownish or greenish background; 6−11 pale bars on body (Figs. 27a, 28a and 29a) or series of short white saddles along back, side of body being then more or less mottled, with midlateral row of small black spots (Figs. 27b, 28b and 29b); often a pale, crescent-shaped, transverse band across anterior nape behind eyes, reaching to pectoral-fin base (band may be absent); no whitish spot at the upper edge of opercle.............. 25

25a (24) When visible, a broad pale crescent-shaped band across anterior nape behind eyes extends onto rear part of eyes; anterior nostril tube without tentacle (Fig. 27)........................ Millerigobius macrocephalus (Kolombatović, 1891)

25b (24) When visible, a broad pale crescent-shaped band across anterior nape behind eyes does not extend onto eyes; anterior nostril with a tentacle (Figs. 28 and 29)............................................................................................ Genus Zebrus: Z. zebrus (Risso, 1827) or Z. pallaoroi Kovačić, Šanda & Vukić, 2021

26a (23) Body translucent or semitranslucent and skin surface poorly pigmented, prominent melanophores form a series along lower body or as caudal-fin mark; other pigments, if present, internal, on vertebrae and organs; fins translucent (Figs. 30, 31 and 32)............................................................................................ 27

26b (23) Body not translucent or only partially translucent and skin with more prominent pigmentation than just a series of melanophores along lower body or a caudal-fin mark; at least some pigment on fins............................ 29

27a (26) Body semitranslucent with 4 elongate black markings along vertebral column and large, conspicuous, triangular black spot at base of caudal fin (Fig. 30)..................................... Pseudaphya ferreri (de Buen & Fage, 1908)

27b (26) Body translucent with row of melanophores along anal-fin base, no triangular black spot at base of caudal fin, no black markings along vertebral column..................................................................... 28

28a (27) Second dorsal fin of moderate length, with I+11–13 rays; side of abdomen with no well defined black spots (Fig. 31).............................................................................. Aphia minuta (Risso, 1810)

28b (27) Second dorsal fin long, with I+18–20 rays; side of abdomen with longitudinal row of 3–4 well-defined tiny black spots (Fig. 32).............................................................. Crystallogobius linearis (Düben, 1845)

29a (26) Body with longitudinal rows or series of dots or small dashes (Figs. 33–39)................................... 30

29b (26) Body without longitudinal rows of dots or small dashes................................................... 35

30a (29) No defined dark dot at posterior angle of mouth (Figs. 33a and 33b)......................................... 31

30b (29) A well-defined dark dot at posterior angle of mouth (Fig. 33c, 33d, 33e and 33f)............................... 32

31a (30) Two longitudinal rows of elongate spots on cheek, one longitudinal mideye stripe (Fig. 34).......................................................................................... Gobius bucchichi Steindachner, 1870

31b (30) No rows of elongate spots on cheek and no longitudinal eye stripe (Fig. 35).............................................................................................. Hazeus ingressus Engin, Larson & Erhan, 2018

32a (30) Ground coloration of body yellow, upper lip unmarked except dot at corner of mouth (Figs. 33c and 36)................................................................................. Gobius auratus Risso, 1810 morph 2

32b (30) Ground coloration of body not yellow, or if body coloration yellow then upper lip with at least one brown or orange mark in addition to dot on corner of mouth (Figs. 37b, 38b and 39b)............................................. 33

33a (32) On eye, upper iris with separate brown dots or radiating stripes, without longitudinal curved mark (Fig. 37b)........................................................................ Gobius incognitus Kovačić & Šanda, 2016

33b (32) On eye, a dark curved mark on upper iris connects longitudinally other marks (Figs. 38b and 39b)................. 34

34a (33) Dark red to light orange dots or tiny spots on body (Fig. 38)........ Gobius xanthocephalus Heymer & Zander, 1992

34b (33) Brown and dark brown dots on body (Fig. 39)...................................... Gobius fallax Sarato, 1889

35a (29) Head and body uniformly yellow (Fig. 40)................................. Gobius auratus Risso, 1810 morph 1

35b (29) Head and body with irregularly scattered dots, midlateral dark marks, mottled brown pattern or any combination of these characters....................................................................................... 36

36a (35) 4–5 well-defined, usually dark-edged, pale dorsal saddles, each terminating with midlateral dark blotch; ventral half of body contrasting white with 10–12 short and narrow brownish bars (Fig. 41)............... Buenia affinis Iljin, 1930

36b (35) No pale dorsal saddles or, if such saddles or blotches present, no short narrow brownish bars on white lower side of body ............................................................................................... 37

37a (36) One black spot on the corner of the mouth, usually followed by two elongate dark spots on ventral part of cheek (Figs. 42 and 43).......................................................... Gobius couchi Miller & El-Tawil, 1974

37b (36) No black spot at corner of mouth..................................................................... 38

38a (37) Body with irregular, zigzag vertical dark bars, 8 or more along lateral midline, sometimes coalescing in upper lateral stripe, 10 or more on lower side, alternating with pale or white interspaces about the same width (Fig. 44)...................................................................................... Gobius ophiocephalus Pallas, 1814

38b (37) No or fewer than 8 dark markings along lateral midline, and/or no multiple alternating dark and pale areas along lower body........................................................................................... 39

39a (38) Eyes high on head, top of eye protruding above dorsal profile; head length no more than 3/5 of caudal-fin length (Figs. 45 and 46)......................................................................................... 40

39b (38) Eye not high on head, their top forming part of dorsal profile, and head length more than 3/5 of caudal-fin length..... 41

40a (39) Body with 5 elongate mid-lateral brown blotches (excluding that on pectoral-fin base) and light blue metallic markings (Fig. 45)........................................................ Oxyurichthys petersii (Klunzinger, 1871)

40b (39) Pale beige background with three slightly oblique brown bars, first bar below first dorsal fin, second and third bars below anterior and posterior parts of second dorsal fin, and large irregular brown spot at caudal-fin base (Fig. 46)...................................................................... Cryptocentrus steinhardti Goren & Stern, 2021

41a (39) Semitranslucent scaleless body with 6 wavy, irregular gray-brown bars and no lateral midline markings (Fig. 47)...................................................................... Hetereleotris vulgaris (Klunzinger, 1871)

41b (39) Body not semitranslucent with gray-brown irregular bars or, if semitranslucent with dark bars and no scales visible, then lateral midline marks present................ Remaining species: Aulopareia unicolor (Valenciennes, 1837), Buenia massutii Kovačić, Ordines & Schliewen, 2017, Coryogalops ocheticus (Norman, 1927), Deltentosteus collonianus (Risso, 1820), Deltentosteus quadrimaculatus (Valenciennes, 1837), Gobius cobitis Pallas, 1814, Gobius gasteveni Miller, 1974, Gobius geniporus Valenciennes, 1837, Gobius niger Linnaeus, 1758, Gobius paganellus Linnaeus, 1758, Gobius roulei de Buen, 1928, Gobius xoriguer Iglésias, Vukić & Šanda 2021, Lesueurigobius sanzi (De Buen, 1918), Papillogobius melanobranchus (Fowler, 1934), Pomatoschistus adriaticus Miller, 1973, Pomatoschistus bathi Miller, 1982, Pomatoschistus knerii (Steindachner, 1861), Pomatoschistus marmoratus (Risso, 1810), Pomatoschistus microps (Krøyer, 1838), Pomatoschistus minutus (Pallas, 1770), Pomatoschistus nanus Engin & Seyhan, 2017, Pomatoschistus norvegicus (Collett, 1902), Pomatoschistus quagga (Heckel, 1837), Pomatoschistus tortonesei Miller, 1968, Silhouettea aegyptia (Chabanaud, 1933) (males of Gobius gasteveni Miller, 1974, Gobius niger Linnaeus, 1758 and Gobius paganellus Linnaeus, 1758 (can have almost entirely dark body and head, see Figs. 53b, 55b and 56b).