Last update: 07 May 2013

Common names:

* proposed name

Synonyms:

*In: Cuvier & Valenciennes, 1837

Etymology:
'Scartelaos' is probably a compound name from the Greek 'skarthmos' (leaping), and 'laos' (people, folk), which maybe refers to the typical tail-stand of males during courtship

'histophorus' is another compound form, from the Greek 'hystos' (pole, mast), and 'phorein' (to bear, to wear), which refer to the narrow and pointed first dorsal fin (Cuvier & Valenciennes, 1837)

Maximum recorded length:
125 mm SL (Murdy, 1989)
140 mm SL (Rainboth, 1996)

Live colouration (Murdy, 1989; Polgar et al., 2010; Takita et al., 2011; pers. obs.: Australia, NT):
ground colour on dorsum and flanks greenish grey: dorsally darker; venter pale blue to whitish; cheek and trunk with scattered bluish to black speckles; 4-8 dark grey to bluish, narrow vertical bars frequently visible on flanks; D1 greenish grey; D2 dusky to greenish grey with tiny bluish spots; caudal fin grey with 3-5 black wavy, broken lines, posterior margin black; anal fin transparent; pectoral and pelvic fins dusky; males of Australian populations have white eye borders (Townsend & Tibbets, 2005)

Colouration on preservation (Murdy, 1989; pers. obs.: Australia, Papua New Guinea, Peninsular Malaysia):
ground colour slate grey to brown, ventrally paler; dusky spots, bars and speckles frequently lacking

Diagnosis (Murdy, 1989):
head depth 10.1-12.4%SL; caudal fin length 18.5-25.1%SL; length of D1 base 5.7-7.5%SL; D2 and anal fins connected by membrane to the caudal fin; barbel on tip of chin (ventral midline), near the symphysis of lower jaw; narrow vertical dark bars on flanks; no large, black spots or stripes basally on posterior half of D2.
The genus is characterised by the presence of barbels on the ventral surface of the head (see drawing)

Diet:
benthic feeder, omnivorous: it feeds on diatoms and small invertebrates (nematodes, ostracods, copepods, etc.: Milward, 1974; Khoo 1966, cited in Clayton, 1993)

Reproduction:
its reproductive behaviour at low tide and out of the burrows has been described by Milward (1974) and Towsend & Tibbets (2005): the males stand on their tails to attract females into their burrows and spawn; other details of its life cycle have not been studied (see also Reproductive behaviour)

left: a reproductive couple; the larger male is on the left; the burrow entrance is on the right

right: a tail stand by a male trying to attract a female from the distance

(photos: G. Polgar, Purutu Is., Fly river delta, Papua New Guinea)

Ecological notes (Polgar & Crosa, 2009; Polgar et al., 2010; Takita et al., 2011; pers. obs.: Australia NT):
during low tide, larger individuals are more abundant at lower levels on tidal flats, below the mean sea level, while smaller individuals are frequently found at higher levels, in mangrove pneumatophore zones (Murdy, 1986; Polgar et al., 2010), and on creek banks (Milward, 1974). S. histophorus can be found in relatively variable environmental conditions during low tide, e.g. on mixed or mud tidal flats, and in areas with different density of tide pools and structural elements (plant debris, pneumatophores, etc.)

left: Morib, Peninsular Malaysia: mudflat; smaller S. histophorus are abundant at higher levels, a few metres from the last row of trees, while larger individuals dig their burrows at lower levels on the mixed tidal flat (photo: G. Polgar, 2006)

right: Ludmilla Creek, Darwin, NT, Australia; larger S. histophorus are here present nearby gullies discharging into the creek's mouth (photo: G. Polgar, 2007)

Distribution:
from Pakistan to Japan and Australia; type locality: Ganges Delta, India (Murdy, 1989)

Remarks:
several authors reported marked and periodical fluctuations of the population size (Milward, 1974; Townsend & Tibbets, 1995)

Photographs of Scartelaos histophorus:

A, B: S. histophorus feeding and interacting at low tide (photo: M. Takata, Okinawa, Japan, 2000); C: close-up (photo: T. Mukai, Japan, 2006)*; D: another close-up (photo: Y. Ikebe, Okinawa, Japan, 2002)*; E: "stand on tail" behaviour of a male during courtship (photo: G. Polgar, Purutu Is., Fly river delta, Papua New Guinea, 2007); F: juvenile of S. histophorus in a plastic bag (photo: G. Polgar, Kuala Lumpur, 2006); G: close-up of a juvenile in aquarium (photo: G. Polgar, Kuala Lumpur, 2006); H: juvenile in a tide pool at low tide, Acanthus sp. zone on a high step behind a mudflat (photo: G. Polgar, Purutu Is., Papua New Guinea, 2007); I: a specimen in aquarium (photo: G. Polgar; collected in Ludmilla Creek, Darwin, NT, Australia, 2007); J: detail of the barbels: note the diagnostic one on tip of chin (photo: G. Polgar; collected in Ludmilla Creek, Darwin, NT, Australia, 2007); K: expelling a bubble of air after air gulping (photo: G. Polgar, Purutu Is., Fly river delta, Papua New Guinea, 2007); L: a couple of adults in aquarium: note the different colour of the eyes' borders (photo: G. Polgar; collected in Ludmilla Creek, Darwin, NT, Australia, 2007)* with permission

Drawings of Scartelaos histophorus:

A	B	C
D		E
F		G

A: cephalic sensory and nasal pores of Scartelaos spp.: an = anterior nostril; ao = anterior oculoscapular canal pore; pn = posterior nostril (modified from Murdy, 1989)*; B: ventral view of the head of S. histophorus: B = barbels (modified from Murdy, 1989)*; C: Scartelaos viridis (Hamilton) (Herre, 1927); D: Scartelaos histophorus (Valenciénnes) by Roger Swainston (Allen, 1997)*; E: Scartelaos viridis (Hamilton) (Koumans, 1953); F: Scartelaos viridis (Hamilton) (Bleeker, 1983)*; G: Gobius viridis Hamilton (Hamilton, 1822) - * with permission