Notoglanidium Günther, 1903

Geerinckx, Tom, Vreven, Emmanuel, Dierick, Manuel, Hoorebeke, Luc Van & Adriaens, Dominique, 2013, Revision of Notoglanidium and related genera (Siluriformes: Claroteidae) based on morphology and osteology, Zootaxa 3691 (1), pp. 165-191 : 174-175

Notoglanidium Günther, 1903

Auchenoglanis (partim): in Boulenger (1902) Liauchenoglanis Boulenger 1916

Platyglanis Daget 1978

Parauchenoglanis (partim) Boulenger 1911 Anaspidoglanis Teugels et al. 1991

Type species Notoglanidium walkeri by original designation.

Diagnosis. The genus Notoglanidium can be distinguished from the other subfamily members ( Auchenoglanis & Parauchenoglanis ) by the following diagnostic characters: eyes small to minute (3.3–13.3% HL) without a free border, covered with transparent skin, situated dorsally on the first half of the head and often somewhat projecting from it; frontals clearly narrower at the level of the eyes than posterior to these; orbita not well demarcated by infraorbital and skull roof bones; sphenotic not bordering orbita; infraorbital canal entering the sphenotic close to the suture with the frontal; first nuchal plate very much or completely reduced, widely separated from supraoccipital process; branches of parapophysis of fourth vertebra well separated by a deep indentation; edge of caudal fin rounded.

Osteology: description and interspecific variation ( Tables 1 & 2 ). Apart from these diagnostic characters, the following osteological characters are useful for identification of the genus and included species. Anterior bifurcation of mesethmoid narrow or wide according to width of premaxillary tooth plate; mesethmoid cornua long in some species ( N. boutchangai , N. macrostoma ). Anterior fontanel spindle- to slightly drop-shaped (broadening posteriorly); mesethmoid bordering anterior third to half of it. Posterior fontanel present in some species ( N. maculatum & N. thomasi ). Nasal bones plate-like ( N. macrostoma ), or usually narrow and tube-like, sometimes reduced ( N. walkeri ) or absent ( N. maculatum & N. thomasi ). All infraorbitals straight, strongly reduced in some species ( N. maculatum & N. thomasi ). Antorbital wedge- to L-shaped or splint-like, depending on the size of the medial portion. Supraoccipital process reduced to a short narrow splint, or nonexistent ( N. maculatum , N. thomasi & N. walkeri ). First nuchal plate weakly developed, not contacting the supraoccipital. Posteriorly oriented fenestra in the otic region of the skull roof present in two species ( N. maculatum & N. thomasi ), separating dorsal portions of parieto-supraoccipital, pterotic and extrascapular.

Combined (left/right) premaxillary tooth plate average to broad, with a width ranging from 10.5–41.7% HL (thus almost filling the mouth width in N. akiri , N. boutchangai & N. macrostoma ). Dentary with anteroventral and/or posteroventral flanges near symphysis, which may be very small; coronoid process low and robust ( N. boutchangai & N. macrostoma ) or high relative to the corpus (others); always reclining somewhat posteriorly, and preceded by a long, anterior, hook-like process on the dorsal face of the dentary in N. maculatum and N. thomasi ( Fig. 12 A). Posterolateral autopalatine flange deep or not. Hyomandibular with an anteroventral ridge or a stub-like process on its outer face ( Fig. 12 B). 8–12 branchiostegal rays. Opercle relatively lower in species with more depressed heads.

Humeral process of cleithrum well developed; dorsoposterior process distinctly present ( Fig. 12 C), partly merged with dorsal articulatory process, or absent. Mesocoracoid with an ‘arch’ on the scapulocoracoid (except in N. maculatum & N. thomasi ). Supraneural small (large in N. pallidum ). Total number of vertebrae 36–50. Hypurals of caudal skeleton partially fused in some species ( N. maculatum , N. thomasi & rudimentarily in N. walkeri ). Dorsal fin with spinelet and spine and 7–22 soft branched rays, pectoral fin with one spine and 5–8 branched rays, pelvic fin with 6 rays (5 of which are branched), anal fin with 9–28 rays (6–24 branched).

Note on the publication date. Whereas many authors have used the name Notoglanidium Günther, 1902 , as suggested by a date mentioned on the original paper of the description of the genus and its type species N. walkeri, Duncan (1937) correctly established the correct date of actual publication (to be included in the taxon names) as being 1903.

Figures

FIGURE 12. CT scan images of selected bones. A, Ventrolateral view of lower jaw of Notoglanidium maculatum. B, Lateral view of suspensorium of N. akiri. C, Lateral view of cleithrum of N. akiri. Anterior to left, not to scale. o-den, os dentale; ohyom, os hyomandibulare; o-mpt, metapterygoideum; o-pop, os preoperculare; o-q, os quadratum; o-ar, os anguloarticuloretroarticulare; pr-a, anterior process; pr-cor, coronoid process; pr-hum, humeral process; pr-hyom, anterodorsal hyomandibular process; pr-pd, posterodorsal process.