Devario pathirana ( Kottelat & Pethiyagoda, 1990 )

Sudasinghe, Hiranya, Pethiyagoda, Rohan & Meegaskumbura, Madhava, 2025, Species without borders: the diversification of giant danios in Sri Lanka (Teleostei, Danionidae, Devario), Evolutionary Systematics 9 (2), pp. 229-258 : 229-258

Devario pathirana ( Kottelat & Pethiyagoda, 1990)

Danio pathirana Kottelat & Pethiyagoda, 1990 .

Material examined.

8 ex., see Suppl. material 1.

Diagnosis.

Devario pathirana is distinguished from Sri Lankan congeners by the combination of the following characters and character states: it is the only completely barred Devario in the island, with 7–11 bars on the side of the body (vs fewer than 4 bars in D. malabaricus , D. micronema , D. memorialis , D. altus ); P-stripe short, ending above the caudal peduncle (P-stripe long, extending uninterrupted above the caudal peduncle in D. malabaricus , D. micronema , D. memorialis , D. altus ); anal-fin origin posterior to origin of dorsal fin, beneath 3 rd branched dorsal-fin ray (vs anal-fin origin on vertical through dorsal-fin origin in D. memorialis ); 1 st infraorbital with an infraorbital process (vs infraorbital process absent in D. malabaricus , D. memorialis ); preanal length 64.9–69.8 % SL (vs 58.5–63.8 % SL in D. memorialis ); caudal peduncle length 15.7–19.6 % SL (vs 19.2–21.4 % SL in D. altus ); caudal peduncle depth 11.3–13.1 % SL (vs 8.1–9.8 % SL in D. memorialis , 8.8–10.5 % SL in D. altus ); body depth 32.4–36.9 % SL (15.9–22.6 % SL in D. memorialis ; 21.8–26.0 % SL in D. altus ); dorsal-fin height 20.6–24.3 % SL (vs 15.7–20.0 % SL in D. memorialis ); dorsal-fin base length 19.0–23.8 % SL (vs 13.5–16.3 % SL in D. memorialis , 15.1–18.2 % SL in D. altus ); anal-fin base length 20.7–22.8 % SL (vs 16.4–20.5 % SL in D. altus ); pelvic-fin height 16.1–18.8 % SL (vs 11.6–13.3 % SL in D. memorialis ; 12.9–16.6 % SL in D. altus ); pectoral-fin height 23.8–27.9 % SL (vs 19.1–23.6 % SL in D. memorialis , 20.3–23.4 % SL in D. altus ); head depth 17.6–21.7 % SL (vs 14.1–15.8 % SL in D. memorialis ); interorbital width 40.7–45.3 % HL (vs 37.2–40.7 % HL in D. memorialis ); rostral barbel 8.6–17.7 % HL (vs 4.0–8.9 % HL in D. memorialis ); 14–15 predorsal scales (vs 17–19 in D. memorialis ); 13–14 circumpeduncular scales (vs 15–18 in D. memorialis ); 8–8 ½ scales between lateral line and dorsal-fin origin (vs 7 ½ in D. memorialis ; 6–7 ½ in D. altus ); 11 ½ branched dorsal-fin rays (vs 8 ½ in D. memorialis ); 13 ½ – 14 ½ branched anal-fin rays (vs 14 ½ – 15 ½ in D. memorialis ).

Devario pathirana is genetically distinct from D. micronema , its closest congener by 1.2–1.6 % for the cox 1 DNA barcoding marker and genetically distinct from rest of the Sri Lankan species of Devario by over 3.6 %.

Habitat and distribution.

Devario pathirana is confined to the streams associated with the headwaters of the Nilwala River basin in the southwestern wet zone of Sri Lanka. The population of Devario in Suriyakanda, at the type locality of Rasboroides rohani in the Walawe basin, comprises of potential hybrids between D. pathirana and D. malabaricus . This is likely a result of an anthropogenic translocation ( Sudasinghe et al. 2018).

Remarks.

At some of the sampling sites in the headwaters of the Nilwala basin, both D. malabaricus and D. micronema were recorded along with D. pathirana (T. Ranasinghe, S. Wijayasekara pers. comm.). This suggests that there may be zones of contact between these species. Sexual dimorphism is apparent in D. pathirana , with males possessing tubercles on the branched rays of the pectoral fin, which are absent in females.