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| Nanosphronemus gemma Britz, Tan & Rüber, 2026 Raffles. Bull. Zool. 74; |
Abstract
A new genus and species of miniature labyrinth fish of the family Osphronemidae, Nanosphronemus gemma, is described from Vietnam. It differs from all other genera of anabantoids by a unique dorsal- and anal-fin ray count, a unique colour pattern and a number of unique or highly unusual skeletal characters. Our molecular phylogenetic analysis indicates that Nanosphronemus is the sister group of the genus Trichopsis, the croaking gouramis.
Key words. Anabantoidei, labyrinth fishes, miniaturisation, gourami
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| Nanosphronemus gemma, live colouration, not preserved, all ca. 16 mm SL in lateral view. a, putative female above, note absence of red stripe in dorsal half; b, putative male in normal colouration, note presence of red stripe above and darker pigmentation below midlateral stripe; c, putative male in breeding colouration, note overall darker colouration of body and also fins, presence of bright red stripe and highly iridescent scales in mid-lateral stripe and below on head and body. |
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| Nanosphronemus gemma, not preserved, all ca. 18 mm SL. a, mature female with eggs; b, in breeding colouration and typical oblique courtship position, c, approaching bubble nest under plant leaf; d, adding air bubbles and embedding eggs into bubble nest. |
Nanosphronemus, new genus
Diagnosis. Nanosphronemus differs from all other genera
in the suborder Anabantoidei by its unique count of XIX–
XXI+2–3 dorsal-fin rays (vs. I–XVIII+ 4–14, rarely XIX
in some specimens of Macropodus ocellatus) and XX–
XXIV+4–5 anal-fin rays (vs. I–XVII+8–38, rarely XX–XXII
in some specimens of Macropodus spp.), the presence (vs.
absence) of a series of anteroventrally directed processes off
the distal part of caudal haemal arches, Baudelot’s ligament ...
Etymology. The new genus name is derived from the Ancient
Greek word, νάνος, meaning dwarf, combined with the name
Osphronemus, the type genus of the family Osphronemidae,
to which this new genus belongs. Gender: masculine. The
name alludes to the tiny size of this new fish, which makes
it one of the smallest anabantoids known to date.
Nanosphronemus gemma, new species
Suggested common name. Jewel Gourami.
Distribution. Unclear at present: reported from undisclosed
area near Huế in Central Vietnam.
Etymology. The species name is derived from the Latin word
for jewel, ‘gemma’, alluding to the stunning colouration of
sexually mature males. A noun in apposition.
Ralf BRITZ, Heok Hui TAN and Lukas RÜBER. 2026. Nanosphronemus gemma, A remarkable New Genus and Species of miniature osphronemid from Vietnam (Teleostei: Anabantoidei: Osphronemidae). Raffles. Bull. Zool. 74; 606–623.
