Devario micronema (Bleeker, 1863)

Sudasinghe, Hiranya, Kottelat, Maurice & Pethiyagoda, Rohan, 2025, The collection of Sri Lankan freshwater fishes reported on by Pieter Bleeker (1863) (Osteichthyes: Cyprinidae, Danionidae, Nemacheilidae), Zootaxa 5647 (5), pp. 461-468 : 462-465

Devario micronema and D. lineolatus

( Figure 1g –k )

Material examined. Putative holotype of Devario micronema and syntype of D. lineolatus, RMNH.PISC.2746.A , 60.0 mm SL, 79.4 mm TL; RMNH.PISC.2746.B , 59.2 mm SL, 76.9 mm TL .

For metric and meristic data, see Table 1 .

Remarks. Bleeker (1863a) reported examining three examples of D. lineolatus (74–80 mm TL) and only one of D. micronema (82 mm TL). The three specimens of Devario in the RMNH collection, however, are in a single lot labelled ‘ Danio micronema Blkr. ’ We exclude the smallest of these (40.7 mm SL; 50.8 mm TL) from consideration as a type of either species given that Bleeker (1863a) reported that the minimum length of the specimens before him was 74 mm TL.

Bleeker (1863a) distinguished Devario micronema from his D. lineolatus as follows: “Cette autre espèce de Danio du Ceylan se distingue de la précédente par un corps plus allongé, un dos beaucoup plus convexe, une forme différente du premier sous-orbitaire, des écailles moins nombreuses, par un nombre moindre des rayons des pectorales et de l’anale, par la bande violette unique des flancs, par l’absence des taches oblongues transversales de la région postbranchiale, etc.” [This other species of Danio [i.e., D. micronema ] from Ceylon is distinguished from the previous one [ D. lineolatus ] by a more elongated body, a much more convex back, a different shape of the first suborbital, by less numerous scales, by a smaller number of rays in the pectorals and the anal [fin], by the single violet band on the flanks, by the absence of the oblong transverse blotches on the postbranchial region, etc].

Referencing RMNH.PISC.2746.A, 60.0 mm SL as ‘ Devario sp. A’ and RMNH.PISC.2746.B, 59.2 mm SL as ‘ Devario sp. B’, the two putative type specimens respond to these criteria as shown below. We additionally report the sex (inferred from the presence of tubercles on the branched rays of the pectoral fin in adult males, absent in females ( Sudasinghe, 2024) and the condition of the first infraorbital; Bleeker’s (1863a) data are in brackets:

	Devario sp. A	Devario sp. B
Body depth	3.3 [4] times	3.3 [3] times
Convexity of dorsum	[more convex]	[less convex]
Pored lateral-line scales	34+1 [34]	35+1 [38]
Dorsal-fin branched rays	9½ [10]	10½ [10]
Anal-fin branched rays	12½ [12]	13½ [14]
Markings on ‘postbranchial’ region	No [no]	Yes [yes]
Infraorbital 1 with a process	Yes	No
Sex	Male	Female

The only Sri Lankan species of Devario to consistently lack bars and/or blotches on the anterior body is D. memorialis (see Sudasinghe et al., 2020a). Neither species of Devario described and illustrated in Bleeker (1863a, 1864) can be D. memorialis , however, for the latter lacks an infraorbital process and also possesses 8½ branched dorsal-fin rays (vs 9½ in Devario sp. A , and 10½ in Devario sp. B ). Further, D. memorialis has the dorsal-fin origin immediately above the anal-fin origin (vs distinctly anterior to the anal-fin origin in all other Sri Lankan Devario including the species illustrated in Tab. 4 of Bleeker, 1864).

In the 11 examples of a highland population of Devario they measured and associated with the name ‘ D. monticola ’ (= D. lineolatus Bleeker ), Batuwita et al. (2017) obtained a body depth of 26–29% SL, less than the body depth of 30% SL in Devario sp. A , and 30% SL in D. sp. B. We therefore exclude also the possibility that Devario sp. A is a representative of this population.

Therefore, the only Sri Lankan species of Devario with which the characters of Devario sp. A are consistent (apart from coloration), is D. micronema sensu Batuwita et al. (2017) . In D. micronema , however, the stripes on the anterior body are fragmented into blotches, a character not visible in Devario sp. A . Even the vertically elongate cleithral blotch common to all Sri Lankan species of Devario is only faintly visible in this specimen ( Fig. 1g ). According to Bleeker (1863a), the single example of Devario sp. A he examined lacked, even at that time, ‘oblong transverse spots on the postbranchial region’. This specimen also has a distinctively arched dorsal profile (a ‘much more convex dorsum’: Bleeker, 1863a). Taken together, these features suggest that some time may have elapsed between the death of the specimen and its preservation, after its colours had faded. We therefore attribute the absence of markings on the postcleithral region of this specimen to a preservation artefact.

Devario sp. A , however, exhibits a process on the 1st infraorbital, a character that is lacking in Devario sp. B . In his description of this bone, however, Bleeker (1863a) mentioned no such character. In the descriptions of both D. micronema and D. lineolatus, Bleeker (1863a) stated, “orbita antice superne spinula brevi antrorsum spectante” [“anterior superior part of orbit with a short, antrorse [forward-pointing] spinule”]. It appears that what he meant was the pointed process at anterior extremity of the supraorbital in some specimens of Sri Lankan Devario (see Fig. 1k ), not the process on the 1 st infraorbital possessed by the species of Devario in the wet-zone lowlands referred to as D. micronema by Batuwita et al. (2017). In an examination of 145 examples of D. malabaricus and 142 examples of D. micronema sensu Batuwita et al. (2017) , Sudasinghe (2024) showed the latter to exhibit a process on the 1 st infraorbital, a character absent in the former.

In the light of the foregoing, we conclude that RMNH.PISC.2746.A ( Devario A, Fig. 1g ) is the holotype of Danio micronema Bleeker. It is consistent with the species of Devario occurring in the lowland rainforests of perhumid south-western Sri Lanka referred to as D. micronema by Batuwita et al. (2017) and subsequent authors including Sudasinghe & Pethiyagoda (2019), Pethiyagoda & Sudasinghe (2021), Sudasinghe et al. (2020), and Sudasinghe (2024).

We further conclude that Devario B ( Fig. 1h ) is a syntype of D. lineolatus . It lacks a process on infraorbital 1 and has an anteriorly bifurcated P-stripe; its metric and meristic data ( Table 1 ) are consistent with the conception of D. malabaricus by Batuwita et al. (2017) and Sudasinghe (2024). We therefore consider Danio lineolatus Bleeker, 1863 , a junior subjective synonym of D. malabaricus (Jerdon, 1849) . Devario lineolatus (Bleeker, 1863) is a secondary homonym of Leuciscus lineolatus Blyth, 1858 ; Batuwita et al. (2017) provided for it the replacement name D. monticola .

Figures

FIGURE 1. Syntypes of Garra ceylonensis, a, RMNH.PISC.2069.A, 88.1 mm SL; b, RMNH.PISC.2069.B, 65.4 mm SL; and c, RMNH. PISC.2069.C, 65.6 mm SL; d, illustration of Garra ceylonensis from Bleeker (1864: p. 1, fig. 4). Holotype of Systomus pleurotaenia: e, RMNH.PISC.2414, 121 mm SL; f, illustration from Bleeker (1864: pl. 3, fig. 2). Devario micronema, g, holotype, RMNH.PISC.2746.A, 60.0 mm SL; h, Devario lineolatus, syntype, RMNH.PISC.2746.B, 59.2 mm SL; and illustrations of i, D. micronema and j, D. lineolatus, from Bleeker (1864: pl. 4, figs. 2,3 resp.); k, D. micronema, recent specimen, DZ3857, 52.4 mm SL, showing process on first infraorbital (io) and shape of ‘spinule’ on supraorbital.