Malagodon, Meinema and Huber, 2023

Carr, Emily M., Martin, Rene P. & Sparks, John S., 2024, A New Extinct Species of Malagodon (Cyprinodontiformes: Pantanodontidae) from Southeastern Coastal Madagascar, with a Discussion of its Phylogenetic Relationships and a Redescription of the Genus, American Museum Novitates 2024 (4012), pp. 1-16 : 5

Malagodon

Figures 2–7

DIAGNOSIS: The primary apomorphic features that separate Malagodon from all other Recent members of mainland African Pantanodontidae are: the presence of oral (external) jaw teeth in both sexes; a pleural rib count of 12–14; the pelvic fins in males are highly modified, with up to the first three pelvic rays becoming notably thickened and spinelike in larger individuals, including the presence of paired claws and hooks on pelvic rays 1–4 (i.e., number of spinelike processes increases, and hooks continue to develop on additional (posterior) pelvic rays as the individual matures; see progression with ontogeny in fig. 6); fully fused hypural plates in the caudal skeleton; and both the dorsal and anal fin of males are notably elongated and produced, with long trailing margins in larger individuals.

Figures

FIGURE 2. Malagodon honahona, new species, holotype, UMMZ 240245, adult male, 23.9 mm SL. Réserve Spéciale de Manombo, southeastern coastal Madagascar. Preserved in ethanol.

FIGURE 3. Malagodon honahona, new species, allotype, UMMZ 254162, adult female, 18.9 mm SL. Réserve Spéciale de Manombo, southeastern coastal Madagascar. Preserved in ethanol.

FIGURE 5. Comparison of adult male and female cleared-and-stained Malagodon species. Malagodon honahona: A, male, AMNH 278989, 20.2 mm SL, and B, female, AMNH 278989, 18.6 mm SL. Malagodon madagascariensis: C, male, AMNH 20526, 22.3 mm SL, and D, female, MNHN 1963-166, 22.2 mm SL. Asterisks (*) mark the neural spine on the fifth vertebral centrum for comparison. Inset on C is of same specimen with additional alizarin staining to visualize neural spines more easily. Scale bars = 1 mm.

FIGURE 6. Ontogenetic series comparing pelvic-fin development during ontogeny in Malagodon males. Malagodon honahona: A, UMMZ 254159, 20.2 mm SL; C, UMMZ 254161, 18.3 mm SL; E, UMMZ 240245, holotype, 23.9 mm SL. Malagodon madagascariensis: B, MNHN 1963-166, 11.8 mm SL; D, MNHN 1963-166, 21.6 mm SL; F, MNHN 1963-166, 26.1 mm SL. S = spinelike process with associated hook. Numerals 1–4 designate hooked segmented rays in series, following thickened spinelike processes, if present. Both spinelike processes and associated hooks increase in number over ontogeny, with sexually mature males possessing both more spinelike processes and hooks: (B) no thickened spinelike process, no hook; (A) no spinelike process, first ray with single hook; (C, D) one spinelike process present, exhibiting single hook, and following ray with paired hooks; (E) two spinelike processes present, with first spinelike process exhibiting single hook, second with paired hooks, and following ray with paired hooks; and (F) three spinelike processes present, all exhibiting paired hooks, and following ray also with paired hooks.

FIGURE 7. Malagodon madagascariensis: A, adult male, MNHN 1963-166, paratype, 20.8 mm SL. B, adult female, MNHN 1963-166, paratype, 17.6 mm SL. Forest streams near Mahambo, northeastern coastal Madagascar. Preserved in ethanol.