
Bull. nat. Hist. Mus. Lond. (Zool.) 64(1): 91-95 
Issued 25 June 1998 

Hetereleotris georgegilli, a new species of 
gobiid fish, with notes on other Mauritian 
Hetereleotris species 

ANTHONY C. GILL 
Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 SBD, UK. 


Synopsis. Hetereleotris georgegilli, described from six specimens, 19.7—22.5 mm SL, is distinguished from congeners by the 
following combination of characters: second dorsal-fin rays I,10—11, usually I,10; anal-fin rays 1,9; scales ctenoid, restricted to 
posterior part of body and caudal peduncle (behind segmented dorsal-fin ray 5—7); and head pores present (posterior nasal, median 
anterior interorbital, posterior interorbital, infraorbital, postorbital and terminal lateral canal pores). Four additional Hetereleotris 
species are recorded from Mauritius: H. apora, H. poecila, H. vinsoni andH. zanzibarensis. The first-named two species represent 
new records for Mauritius. Limited data suggest that Mauritian Hetereleotris assort into different habitats. 
INTRODUCTION 
In 1995 the author participated in a six-week expedition.to survey 
shorefishes of Mauritius, Indian Ocean, along with associates from 
the Smithsonian Institution, J.L.B. Smith Institute of Ichthyology 
and Port Elizabeth Museum. Among the fishes collected were six 
specimens of a new species of the genus Hetereleotris Bleeker, 
1874. The new species is herein described and compared with 
congeners; other Mauritian Hetereleotris species are also dis- 
cussed. 
Hetereleotris species are distinguished from other gobiids by the 
following combination of characters: half or more of lower part of 
first gill slit closed by membrane; distinct, single-lobed mental 
frenum; distinctive superficial neuromast arrangement below eye 
(see Figs 1,2); first dorsal fin with six spines and pterygiophore 
formula of 3-22110; and vertebrae 10 + 17 (Akihito & Meguro, 
1981; Hoese, 1986). 
The genus is most diverse in the western Indian Ocean, with 13 
species (revised by Hoese, 1986); the present study brings the total 
to 14. Only one described species [H. poecila (Fowler)] is known 
from the Pacific Ocean, but it also occurs in the Western Indian 
Ocean. However, Hoese (1986) noted that three undescribed species 
occur in the Pacific (one from the West Pacific, one from Rapa and 
one from Easter Island), and Gill & Reader (1992) recorded an 
additional undescribed species from Middleton and Elizabeth reefs, 
southern Coral Sea. 
MATERIALS AND METHODS 
Measurements to the snout tip were made to the midanterior tip of 
the upper jaw; standard length (SL) from the snout tip to the 
midposterior part of the hypural plate; head length from the snout 
tip to the posterior (vertical), fleshy edge of the operculum. Eye 
diameter was measured horizontally where greatest. Preanal, 
predorsal and prepelvic lengths were measured from the snout tip 
to the anterior edge of the first spine base of the relevant fin. 
© The Natural History Museum, 1998 
Distance between first and second dorsal-fin origins was meas- 
ured between the anterior edges of the first spine base of each fin. 
Caudal peduncle depth was the shallowest depth of the peduncle. 
Caudal peduncle length was measured from the posterior edge of 
the last anal-fin ray base to the ventral edge of the caudal pedun- 
cle at the vertical through the posterior edge of the hypural plate. 
Fin ray lengths were measured from the bases of the rays to their 
tips. Caudal fin length was the length of the lowermost ray articu- 
lating with the upper hypural plate (i.e., hypurals 3 + 4). Pectoral 
fin length was the length of the longest ray. Pelvic fin length was 
measured from the base of the spine to the distal tip of the fourth 
segmented ray. The pattern of interdigitation of first dorsal-fin 
pterygiophores with neural spines is given as a first dorsal 
pterygiophore formula following the methods of Birdsong ef al. 
(1988). Terminology of head pores and other methods of counting 
and measuring follow Hoese (1986) or are self explanatory. Os- 
teological details were determined from radiographs and from a 
paratype that was cleared and stained for cartilage and bone 
(Potthoff, 1984). Meristic and morphometric values are given first 
for the holotype, followed where different by value ranges or 
frequency distributions for the paratypes. Frequency distributions 
are presented in the form ‘x fy,’ where ‘x’ is the count and ‘f’ 
indicates that the following value, ‘y, is its frequency. Where 
counts were recorded bilaterally from the holotype, both values 
are presented and separated by a slash; the first value given is the 
left count. 
Comparisons of H. georgegilli with congeners were based on 
published data (particularly those provided by Akihito & Meguro, 
1981, and Hoese, 1986), specimens obtained in Mauritius by 
the author and colleagues (see below; museum codes follow 
Leviton ef al., 1985), and the following specimens in The Natural 
History Museum: H. bipunctata Tortonese, 1976, Yemen, Aden, 
BMNH 1985.7.29.3-6 (3); H. diademata (Riippell, 1830), Gulf of 
Suez, BMNH 1925.12.31.51 (1; holotype of Lioteres (Pseudo- 
lioteres) simulans Smith, 1958); H. vulgare (Klunzinger, 1871), 
Red Sea, BMNH 1979.6.20.40-43 (4); H. zonata (Fowler, 1934), 
South Africa, Durban, BMNH 1919.4.1.21—22 (2), Persian 
Gulf, BMNH 1900.5.8.93 (2), Mekran Coast, BMNH 1899.5.8.93 
(1). 
