
MAURITIAN HETERELEOTRIS 
reducing to | or 2 rows posteriorly, the teeth of outer row largest and 
caniniform; inner row of teeth across front of premaxilla slightly 
curved and enlarged; dentary with 3 or 4 irregular rows of conical 
teeth anteriorly, reducing to a single row posteriorly, the outer row of 
teeth largest and caniniform; inner row of teeth across front of 
dentary slightly curved and enlarged; palatine and vomer edentate; 
tongue edentate and weakly rounded to truncate, sometimes with 
weak indentation anteriorly. 
Cephalic sensory pores (see Fig. 2): posterior nasal 1/1; anterior 
interorbital |; posterior interorbital 1; infraorbital 1/1; postorbital 1/ 
1; lateral canal 0/0; terminal lateral canal 1/1. Distribution of super- 
ficial neuromasts (cutaneous papillae) on head as shown in Fig. 2. 
Male urogenital papilla pointed posteriorly, with inconpicuous lobe 
on either side of narrow gonopore, the posterior edge of papilla 
papillose; female urogenital papilla subrectangular, truncate, with 
weak lobe on each side of wide gonopore, the gonopore rim papil- 
lose. Epaxial musculature extending anteriorly to posterior 
interorbital pore. 
As percentages of SL: head length 32.0 (30.7—32.4); eye diameter 
9.6 (9.0-10.1); head width at posterior preopercular margin 24.9 
(23.3—28.0); head depth at posterior preopercular margin 18.8 (17.5— 
19.7); body depth at pelvic-fin origin 20.3 (18.4—20.2); body depth 
at anal-fin origin 16.8 (16.2—17.2); caudal peduncle depth 11.2 
(10.2-11.1); caudal peduncle length 19.3 (17.9-19.6); predorsal 
length 40.1 (38.1—39.4); prepelvic length 30.5 (28.9-31.3); preanal 
length 58.9 (58.6—60.0); distance between first and second dorsal- 
fin origins 19.3 (17.9-20.7); second dorsal-fin base length 27.4 
(27.6—28.8); third dorsal-fin spine length 10.7 (11.6—14.3); third 
from last segmented dorsal-fin ray length 14.7 (14.5—16.1); anal-fin 
base length 23.9 (21.7—23.3); third from last segmented anal-fin ray 
length 14.7 (14.6-15.7); pectoral fin length 29.4 (27.1—30.5); pelvic 
fin length 22.8 (19.6-23.2); caudal fin length 24.9 (24.4-26.3). 
COLOUR OF PRESERVED SPECIMENS. Head and body pale brown 
with dusky brown to grey-brown reticulate mottling, this darkest 
dorsally; mottling forming about eight weak bars, the first through 
upper base of pectoral fin, the last through base of caudal fin; last bar 
dark grey, distinctly darker than all other bars; dusky grey bar 
extending from anteroventral edge of eye to middle of upper lip, 
contiguous ventrally with dusky grey bar or spots on lower lip and 
Fig.5 Hetereleotris georgegilli, holotype, USNM 344315, 19.7 mm SL, 
outline of pelvic fins in ventral view. 
Fig.6 Hetereleotris georgegilli, holotype, USNM 344315, 19.7 mm SL, 
diagram of posterior part of body and caudal peduncle showing 
scalation. Arrow indicates vertical through posterior edge of hypural 
plate. 
chin; dark grey spot on upper part of pectoral-fin base, this extending 
on to basal third of upper few rays; dorsal fins pale to hyaline with 
diffuse dusky bars extending obliquely from each body bar; dorsal 
fin sometimes with dark grey distal margin (observed only in two of 
three males); anal fin pale to hyaline, sometimes with two or three 
irregular dusky grey stripes; caudal fin pale to hyaline, with dark 
grey basal bar (see above) and about five to eight irregular dusky 
bars; pectoral fins pale to hyaline with dark grey spot dorsally (see 
above) and irregular dusky bars; large white spot immediately below 
and behind dark spot on upper part of pectoral fin, the white spot 
edged posteriorly in dusky to dark grey; pelvic fins pale, sometimes 
with scattered melanophores basally. 
COLOUR IN LIFE. Not recorded. 
ETYMOLOGY. ‘The specific epithet is in memory of my father, 
George Burton Gill (1925-1994). 
COMPARISONS WITH OTHER HETERELEOTRIS SPECIES. Hoese’s 
(1986) key to western Indian Ocean Hetereleotris identifies speci- 
mens of H. georgegilli as H. nebulofasciata (Smith, 1958), a species 
currently known only from east Africa (Kenya to Mozambique) and 
the Comores (R. Winterbottom, pers. comm.). Hetereleotris 
georgegilli and H. nebulofasciata differ from congeners in having 
the following character combination: scales confined to posterior 
part of body and caudal peduncle; head pores present; and 
preopercular pores absent. The two species also have a similar 
preserved colour pattern. However, H. georgegilli differs from H. 
nebulofasciata in having: fewer segmented rays in the second dorsal 
fin (10-11, usually 10 versus 11); fewer segmented anal-fin rays (9 
versus 9-10, usually 10); more pectoral-fin rays (16-18, usually 18 
versus 15-16); ctenoid scales (versus cycloid); fifth segmented 
pelvic-fin ray unbranched and short (versus relatively well-devel- 
oped, slightly shorter than fourth segmented ray, unbranched or 
branched once); and a prominent dark spot on the dorsal part of the 
pectoral fin (lacking in H. nebulofasciata). 
Hetereleotris georgegilli resembles H. apora (Hoese & Winter- 
bottom, 1979) from Mauritius (see below), South Africa, Saint 
Brandon Shoals, the Comores and the Chagos Archipelago in hav- 
ing: scales ctenoid and confined to caudal peduncle; and fifth 
segmented pelvic-fin ray reduced (usually absent in H. apora). 
Hetereleotris apora differs fron H. georgegilli in having: two 
prominent opercular spines (versus spines lacking); fewer lateral 
scales (4-6 versus 10—13); no head pores (versus head pores present); 
fewer pectoral-fin rays (15-16 versus 16-18, usually 18); more 
segmented second dorsal-fin rays (10-11, usually 11 versus 10-11, 
