Gobius fallax Sarato, 1889

Herler, J., Patzner, R. A. & Sturmbauer, C., 2005, A preliminary revision of the Gobius auratus species complex with redescription of Gobius auratus Risso, 1810, Journal of Natural History 39 (14), pp. 1043-1075 : 1059-1064

Gobius fallax Sarato, 1889

( Figures 2C , 3C , 5 )

Material

Eastern Mediterranean: Italy (n 54): 1♀, 45.8 + 12.6 mm, 2 „„, 46.6 + 13.3 and 48.5 + 12.6 mm, and one juvenile, 21.2 + 6.4 mm, Trieste, near Miramare , July 1999, J. Herler. Slovenia (n 524): 12♀♀, 42.5 + 12.5 to 58.0 + 15.8 mm, 9 „„, 43.8 + 12.2 to 71.6 + 20.6 mm, and three juveniles, 26.1 + 7.4 to 31.5 + 8.6 mm, near Piran, August 2000 and May 2001, J. Herler. Croatia (n 526): 12♀♀, 30.5 + 8.8 to 55.3 + 15.2 mm, 9 „„, 36.1 + 10.4 to 62.9 + 18.7 mm, and five juveniles, 17.3 + 5.2 to 29.9 + 8.7 mm, Island of Cres (west), near Martinscica, September 2000 and May 2001, J. Herler. Two females and two males are stored at the Naturhistorisches Museum Wien ( NMW 94849–94852 ) .

Compared material

Western Mediterranean: France (n 53): three syntypes ( MNHN 1888 /0261–1888/0263, in poor condition), Nice, 1888, C. Sarato. Spain (n 51): 1 „, 54.6 + 14.8 mm, Balearics, Ibiza (north), near Portinatx, 17 September 1997, R. Patzner. Eastern Mediterranean: Greece (n 55): 2♀♀, 42.5 + d and 46.7 + 11.3 mm and 2 „„, 42.8 + 10.4 and 51.5 + 15.7 mm ( SMF 10803–10806 ), east Peloponnes, Palaea Epidavros, June 1970, H. Bath; 1♀, 42.9 + d mm ( NMW 77932), north-western Greece, Bay of Parga, September 1980, B. Sagmeister. Croatia (n 54): 1 „, 38.2 + 8.4, 1♀, 50.3 + 12.9, and two juveniles, 27.6 + 8.4 and 31.9 + 9.1, Island of Solta , June 2000, M. Kovačić .

Identification

Maximum total length about 9 cm. Strict benthic behaviour. Basic coloration grey to olivegreen, with conspicuous brown dotted longitudinal lines. In life easily confused with Gobius bucchichi but with the head more tipped and a larger mouth. Body in G. fallax rather torpedo-shaped and longitudinal rows of dots more abundant and distinct, therefore showing darker coloration as the former. Dark pectoral spot usually visible in living specimens. Yellowish coloration occurs sometimes on the eye rim and on snout. Pelvic disc emarginate, one-quarter to one-third of its length. C rounded. Important meristics are D2 I/14 (13–14), A I/13 (10–14) and LL 43–44 (40–46).

General morphology

Morphometrics of northern Adriatic and Greek specimens given in Table II. Body moderately elongate, laterally compressed and of dorsoventral symmetrical shape. Head large, almost one-third of SL, and somewhat tipped. Mouth oblique and large (UJ 11% in SL), jaw angle below middle of pupil. Snout oblique, shorter than eye. Eyes large, diameter about 29% of H, dorsolateral with narrow interorbital space. Caudal fin rounded, shorter than head. Swim bladder well developed.

Fins (Table III)

D1 VI, D2 I/13–14, A I/12–13 (10–14), C 14 (13–15) branched rays, P 18–19 (17–20), V I/ 5 + 5/I. Fin bases or lengths given in Table II. D1-spines not elongate, only fifth may slightly project. Narrow interdorsal space without membrane. D2 origin anterior of A origin. Rear tips of D2 and A reaching C origin, especially in males during breeding season. C rounded, rarely truncate. P, when pressed against the body, reaching back to below D2 3 rather in females and small specimens, in males to below D2 1 or D2 2. Three uppermost P-rays free from membrane. Pelvic disc with distinct emargination and reduced anterior membrane, which is not more than a skin fold in most specimens ( Figure 2 ). Longest tips usually reach or exceed anus, latter rather in males than in females.

Scales

LL 43–44 (40–46; Table III); TR 12 (11–14). Trunk scales mostly ctenoid. Cycloid scales only anterior of imaginary line from dorsal P-base to middle or end of D1-base and from ventral P-base to V-origin. Cheek naked. Nape, including predorsal area, opercle and pectoral base with small cycloid scales. Larger cycloid scales on breast.

Coloration ( Figure 3C )

In life, greyish to olive-green basic coloration, with remarkable longitudinal rows of brown dots almost forming confluent lines. Most distinct series in lateral midline on trunk, formed by dark brown spots. Above, three series of lighter brown colour, with median row somewhat wavy and originating from orbit. One to two irregular rows below lateral midline. In most specimens especially in females three tiny transversal and parallel bars are found on the lateroventral side of the abdomen between V-origin and anus. Predorsal area densely mottled with numerous brown dots. Large brown dots, centred black, forming lines on median fins. Four longitudinal series on D1, three on D2 and one on A, and five vertical on C. Head with one evident brown line running from the lower orbit to the dorsal P-base, anteriorly continued from the orbit to the upper lip. Many radial stripes on eyes, from pupil to rim of orbit. A V-shaped pattern on snout, from both orbits to median upper lip. Three distinct brown, double spots between jaw angle and preopercle. Numerous white spots on cheek, white and brown spots on opercle, latter continue the line from orbit. Four spots on pectoral base, the usual dark pectoral spot and one small anterior of it, and two other small dots ventrally. In most specimens, five dark geniohyoid dots, lower lip with vertical brown stripes and one dark dot in posterior corner, and dark stripe across upper lip. Local variations are given by certain populations at the western coast of the Island of Cres, Croatia, where the specimens can show a brighter basic coloration and lighter brown mottling than the specimens in the Gulf of Trieste. After preservation in 70% ethanol, the basic coloration pattern remains: weak broad, brown bands run vertically across the head and trunk. The most distinct patterns which remain are the dark row in lateral midline, formed by about 10 blotches connected by smaller dots, the median row above, dark geniohyoid dots, brown and white dots on cheek and opercle, and the four dots on the Pbase, including the large black pectoral spot, edged white posteriorly. Median fins appear grey with dark dotted lines, four on D1, three on D2, one on A and five in C. Many specimens, especially males, exhibit a dark grey head when preserved.

Lateral line system

The head canal system is fully developed with anterior and posterior oculoscapular canal and preopercular canal, with pores Ơ, λ, Κ, ω, α, β, ρ; ρ 1, ρ 2, and γ, δ, E, respectively. The numbers of head neuromasts are shown in Table IV. The typical arrangement is shown in Figure 5 . Suborbital rows 2 and 3 rarely reaching and not exceeding longitudinal row d. Nevertheless, latter often separated in two or three sections. Row 5 usually divided into superior and short inferior section by row b. Row 6i usually reaches or exceeds level of d, rarely shorter. Row ‘‘ α ’’ always present as single papilla near pore α but showed three papillae on the right head side of one specimen. Last papilla of oculoscapular rows x1 and of row u sometimes with a ventral extension, indicating a row tr, but with uncertain assignation. Left and right rows o usually separated in dorsal midline, but confluent in some specimens. Trunk rows ld1 (7–18 papillae), ld2 (2–7), ld3 (3–16), lv1 (13–25), lv2 (6–18), lv3 (8–20), and 27–31 median series ltm (up to 19 papillae, longest rows below D1 and on caudal peduncle). Three longitudinal rows lc (21–52) on caudal fin.

Biology

In the northern Adriatic, G. fallax was found in shallow water, most frequently at 2–8 m depth on little-sloping bedrock coasts. It exhibits a strong benthic behaviour and prefers horizontal slits with sand bottom at the base of rocks as shelter. Details on the habitat choice will be given in a separate paper.

Figures

Figure 2. Morphology of the pelvic disc of closely related Gobius species. (A) G. auratus (colour morph 1), MNHN 1988-630 (neotype of G. auratus by Heymer and Zander 1992), male, 57.1 + 15.0 mm (right fourth ray damaged); (B) G. auratus (colour morph 2), female, 60.7 + 16.5 mm; (C) G. fallax, female, 55.3 + 15.2 mm; (D) G. xanthocephalus, male, 55.4 + 15.2 mm. Scale bar: 5 mm.

Figure 3. Life coloration of (A) G. auratus (colour morph 1: central Adriatic, Island of Murter, Croatia); (B) G. auratus (colour morph 2: northern Adriatic, Island of Cres, Croatia); (C) G. fallax (northern Adriatic, Island of Krk, Croatia); (D) G. xanthocephalus (western Mediterranean, Banyuls-sur-Mer, France). Scale bar: 1 cm.

Figure 5. Lateral line system of G. fallax, male, 48.5 + 12.6 mm, from the northern Adriatic Sea in dorsal (A), lateral (B) and ventral (C) view. Scale bar: 5 mm.