Wednesday, July 10, 2019

[Ichthyology • 2019] A Redescription of the Bearded Gudgeon, Pogoneleotris heterolepis (Günther, 1869) (Gobioidei: Butidae)


Pogoneleotris heterolepis (Günther, 1869)

in Larson & Hui, 2019. 
 RAFFLES BULLETIN OF ZOOLOGY.  67 

Abstract
 The poorly known butid gudgeon Pogoneleotris heterolepis is redescribed based on 15 specimens obtained from fish markets and local fishers from 1982 to 2018, plus examination of the holotype. It is unique among butids in having a longitudinal papilla pattern and the preopercular canal continuous with the oculoscapular canal and is one of only two gobioids (other than Rhyacichthys and Terateleotris) known to have this latter condition.

 Key words: riverine fish, Borneo, aquatic biodiversity, Butidae, Pogoneleotris


TAXONOMY
 Pogoneleotris Bleeker, 1875: 107

 (type species Eleotris heterolepis Günther, 1869,
 by original designation and monotypy). 

Pogoneleotris heterolepis (Günther, 1869)

Eleotris heterolepis Günther, 1869445 (type locality: Malaysia: Borneo: Sarawak).
Pogoneleotris heterolepis – Bleeker, 1875107 (Borneo); Vinciguerra, 1926: 543, pl. 1; Koumans, 1953: 323; Tortonese, 1963: 342; Kottelat & Lim, 1995: 247; Larson in Randall & Lim, 2000: 639; Larson & Murdy, 2001: 3577; Parenti & Lim 2005: 194; Atack, 2006: 167; Kottelat, 2013: 395; Tan & Grinang, 2018: 203–210.

Diagnosis. First dorsal fin VI; second dorsal fin I,11–12; anal fin I,10; pectoral fin 20–23, usually 22; 17 segmented caudal fin rays in 9/8 pattern, branched caudal fin rays 15- 17, usually 15 in 8/7 pattern, procurrent caudal elements 11–15 dorsally, 11–13 ventrally; lateral scales about 38–64, counting main rows only (difficult to see scale rows due to many auxiliary scales); TRB 15–25. Vertebrae 10+16=26 (n = 15); dorsal pterygiophore pattern 3-22110; epurals 2; 2 anal pteryiophores before first caudal vertebra. Pelvic fins separate, space between fin bases scaled. Body with large scales, ctenoid scales alternating with clusters of cycloid scales and auxiliary scales present. Teeth sharp, in about six rows in both jaws. Sensory canals and pores mostly obscured by skin and sensory papillae, but canal extends from pore just above upper lip continuously to rear of opercle; pores usually at ends of branches from main canal; four preopercular pores present, in canal continuous with oculoscapular canal. Sensory papillae in longitudinal pattern, papillae themselves are mostly elongate thin flaps or variously branched, others are seated in oval pits on cheek. Known only from estuarine rivers in Sarawak, Malaysia.

Fig. 4. Fresh Pogoneleotris heterolepis from Simunjan, Sarawak; ZRC56949, female above (166.7 mm SL), male below (160.0 mm SL).
 Fig. 5. Simunjan River habitat of this species; showing fishers’ boat moored beside lines onto bank from gill net.

Fig. 2. Dorsal view (right side reversed) of head of fresh Pogoneleotris heterolepis (ZRC56949, 160.0 mm SL male); showing extent of scalation and sensory papillae.

Habitat. Known only from estuarine habitats; found in turbid rivers with mud substrate (Fig. 5). Tan & Grinang (2018) describe the habitat from which these came, and dissected one specimen (which contained crustacean remains).

Remarks. It is commonly known as the bearded gudgeon, Ikan buccat butta or Batu betutu, and has been referred to as the Sarawak mud gudgeon. At the Rajang River delta, the local name in the Melanau dialect is Ilong mapak [=blind fish] (Tan & Grinang, 2018). 

This species’ conservation status has not been assessed by the IUCN. As it is regularly consumed by the local people and is restricted to mangrove habitats (which are generally threatened throughout South-east Asia), its conservation status deserves assessment sooner rather than later. 


 Helen K. Larson and Tan Heok Hui. 2019. A Redescription of the Bearded Gudgeon, Pogoneleotris heterolepis (Günther, 1869) (Teleostei: Gobioidei: Butidae). RAFFLES BULLETIN OF ZOOLOGY.  67: 385–390.  

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