Ranatra biroi, Lundblad, 1933

Tran, A. D. & Zettel, H., 2021, Taxonomy of the Ranatra biroi group sensu Lansbury, 1972 (Nepomorpha: Nepidae), with descriptions of two new species, Raffles Bulletin of Zoology 69, pp. 507-521 : 508-509

Key to species of the Ranatra biroi group

1. Body length at most 19.5 mm; paramere with short apical hook, tip of apical hook similar to tip of fish hook with a broad barb ......................................................... R. titilaensis (p. 519)

– Body length about 20.0 mm or greater; paramere not modified as above ...................................................................................2

2. Body length excluding siphon around 28.0–30.0 mm (males), 28.5–33.0 mm (females); eye width much greater than interocular space, around 1.4–1.5× interocular width............3

– Body length excluding siphon around 19.9–27.0 mm (males), 21.8–29.0 mm (females); eye width around 0.9–1.3× interocular width ........................................................................................4

3. Space between middle coxae subequal to space between hind coxae; hind femur slightly surpassing anterior margin of operculum ................................................ R. flagellata (p. 509)

– Space between middle coxae clearly narrower than space between hind coxae; hind femur reaching to about half of operculum .................................................. R. digitata (p. 509)

4. Paramere with pointed tooth-like elevation on inner margin of apical hook ( Figs. 1B–E , 2G ) .................................................5

– Paramere without pointed tooth on inner margin of apical hook .........................................................................................8

5. Posterior margin of metasternum straight or slightly concave; paramere with inner margin of apical hook with acute toothlike elevation, tip of apical hook distinctly expanded ( Figs. 1B , 2G ) ...........................................................................................6

– Posterior margin of metasternum convex; paramere with inner margin of apical hook with obtuse tooth-like elevation, tip of hook not strongly expanded ( Fig. 1C–E ) ...............................7

6. Vertex usually lower than eye, thus not visible in lateral view; basal part of fore femur slender, about 1.2× as wide as distal part; posterior margin of metasternum straight........................ ........................................................................ R. biroi (p. 510)

– Vertex higher than eye, visible in lateral view ( Fig. 2C ); basal part of fore femur broader, about 1.5× as wide as distal part; posterior margin of metasternum slightly concave .................. ......................................... R. luzonensis , new species (p. 513)

7. Posterior margin of metasternum clearly convex; hind femur reaching only anterior third of operculum ............................... ............................................................. R. natunaensis (p. 510)

– Posterior margin of metasternum only slightly convex; hind femur reaching or surpassing apex of abdomen ...................... ..................................................................... R. rafflesi (p. 510)

8. Ventral margin of paramere with low elevation or low process before apical hook, apical hook broadly curved or inner space of hook wide............................................................................9

– Ventral margin of paramere without process before apical hook, apical hook strongly recurved and inner space of apical hook narrower.................................................................................13

9. Posterior margin of metasternum convex; paramere medially broadened, apical hook circular (evenly curved) ( Fig. 4B, C ) ....................................................... R. cardamomensis (p. 519)

– Posterior margin of metasternum straight or slightly emarginated; paramere more slender, apical hook more strongly recurved at base, distal part of hook finger-like......................................10

10. Paramere with distal third gradually tapering towards apical hook, dorsal margin almost straight .............. R. recta (p. 514)

– Paramere with distal part dorso-ventrally constricted, thus dorsal margin concave distally ........................................................11

11. Paramere with pre-apical elevation on ventral margin angular, tip of apical hook narrowly rounded; hind femur only reaching about anterior half of operculum ................. R. incisa (p. 514)

– Paramere with pre-apical elevation broad and blunt, tip of apical hook slightly expanded; hind femur nearly reaching apex of operculum or connexivum ....................................................12

12. Paramere with tip of apical hook truncate; space between middle coxae distinctly narrower than space between hind coxae ...... ..................................................................... R. nieseri (p. 514)

– Paramere with tip of apical hook evenly rounded ( Fig. 3F ); space between middle coxae about as wide as space between hind coxae................... R. palawanensis , new species (p. 514)

13. Paramere with apical hook slender, gap between hook and main part very narrow, tip of hook narrow.............................. ...................................................................... R. libera (p. 519)

– Paramere with apical hook shorter and thicker, gap between hook and main part wider, tip of hook broadened...............14

14. Vertex without tubercle; space between middle coxae wide, about 1.6× space between hind coxae; metepisternum with small tufts of setae ................. R. longipes celebensis (p. 517)

– Vertex usually with low conical tubercle; space between middle coxae narrower than space between hind coxae; metepisternum without small tufts of setae...................................................15

15. Paramere with incipient obtuse elevation on inner margin of hook ( Fig. 4A )........................... R. longipes longipes (p. 516)

– Paramere without incipient obtuse elevation on inner margin of hook.............................................................. R. thai (p. 518)

Figures

Fig. 1. Parameres of Ranatra species. A, Ranatra digitata, from Sri Lanka (ZRC_ENT00013064); B, R. biroi, from Irian Jaya, Indonesia; C, R. rafflesi, holotype; D, R. rafflesi, from West Kalimantan, intermediate form (ZRC_ENT00013018); E,R.rafflesi, from West Kalimantan, slender form (ZRC_ENT00013054). C, D, E same scale.

Fig. 2. Ranatra luzonensis, new species, male holotype. A, habitus; B, head, prothorax, and fore legs, dorsal view; C, head and prothorax, lateral view; D, antenna; E, metasternum; F, operculum; G, left paramere, lateral view. B, C same scale; E, F same scale.

Fig. 4. Parameres of Ranatra species. A, R. longipes longipes, from Brunei; B, R. cardamomensis, from Natuna Island (ZRC_ ENT00013061); C, R. cardamomensis, from southern Thailand (ZRC_ENT00013063). B, C same scale. Note that the paramere hook of the Thai specimen (Fig. 4C) recurved further after being dry-mounted from an alcohol-preserved specimen; while still in alcohol, the apex was same as that in the type specimens.

Fig. 3. Ranatra palawanensis, new species, male paratype. A, habitus; B, head, prothorax, and fore legs, dorsal view; C, head and prothorax, lateral view; D, antenna; E, metasternum; F, left paramere, lateral view. B, C same scale.