Labiobaetis

Shi, Weifang & Tong, Xiaoli, 2014, The genus Labiobaetis (Ephemeroptera: Baetidae) in China, with description of a new species, Zootaxa 3815 (3), pp. 397-408 : 406-407

Key to known mature nymphs of Oriental Labiobaetis species

(excluding 4 species which are known only from the imago stage)

1. Six pairs of gills (abdominal segment I without a pair of gills)................................................. 2

- Seven pairs of gills (abdominal segment I with a pair of gills)................................................... 9

2 Hind wing pads present or reduce to small vestige............................................................ 3

- Hind wing pads absent................................................................................. 6

3 Plane of right mandible between incisor base and molar region with a distinct protuberance........................... 4

- Plane of right mandible between incisor base and molar region smooth without any protuberance...................... 5

4 Posterior marginal spines rounded on terga I–IV, but getting narrower and longer on terga V-X; coloration of all abdominal terga pale except for tergum V with a dark brown irregular marking................................................................................................ L. ordinatus (Müller-Liebenau & Hubbard) n. comb. ( Sri Lanka)

- Posterior marginal spines rounded with wide base on all terga; coloration of all abdominal terga brown except for 2 pairs of small cream submedial dots on each tergum................. L. numeratus (Müller-Liebenau) n. comb. ( China, Malaysia)

5 Labrum submarginal setae simple and glabrous; terminal segment of maxillary palpus slightly concave near apex............................................................. L. moriharai (Müller-Liebenau) n. comb. ( Malaysia, Vietnam)

- Labrum submarginal setae spatulate and serrated apically; terminal segment of maxillary palpus with a distinct notch at mesoapical 1/3...................................................... L. mustus (Kang & Yang) n. comb. ( China)

6 Antennal scape with a distinct lobe at distolateral margin...................................................... 7

- Antennal scape without lobe at distolateral margin; submarginal setae on labrum spatulate with serrated apex..................................................................... L. sumigarensis (Müller-Liebenau) n. comb. ( Philippines)

7 Submarginal setae on labrum spatulate with un-serrated or round apex............................................ 8

- Submarginal setae on labrum spatulate with serrated or split apex...................................................................................................... L. molawinensis (Müller-Liebenau) n. comb. ( Philippines)

8 Terminal segment of maxillary palpus with a slightly concave near apex; the 3rd segment of the labial palpus wider than the inner apical lobe of the 2nd segment................... L. geminatus (Müller-Liebenau & Hubbard) n. comb. ( Sri Lanka)

- Terminal segment of maxillary palpus with a distinct concave near apex; the 3rd segment of the labial palpus nearly the same width as the inner apical lobe of the 2nd segment.............. L. diffundus (Müller-Liebenau) n. comb. ( China, Malaysia)

9 Hind wing pads present................................................................................ 10

- Hind wing pads absent; submarginal setae on labrum feathered and in nearly contiguous row; antennal scape with a distinct lobe at distolateral margin...................................... L. difficilis (Müller-Liebenau) n. comb. ( Malaysia)

10 Submarginal setae on labrum spatulate with serrated or split apex.............................................. 11

- Submarginal setae on labrum simple or feathered........................................................... 12

11 Abdominal terga II to IX each with a large contrasting anchor-shaped brown marking,........... L. ancoralis n. sp. ( China)

- Abdominal terga II to IX each with a pair of small cream submedial oblique dashes and a pair of small cream submedial dots in midregion.......................................... L. atrebatinus orientalis (Kluge) ( China, Japan, Korea, Russia)

12 Submarginal setae on labrum simple and glabrous........................................................... 13

- Submarginal setae on labrum feathered................................................................... 14

13 Posterior marginal spines on terga large; coloration of abdominal tergum V not paler than adjacent terga.................................................................. L. pulchellus (Müller-Liebenau & Hubbard) n. comb. ( Sri Lanka)

- Posterior marginal spines on terga small; coloration of abdominal tergum V much paler than adjacent terga............................................................................ L. multus (Müller-Liebenau) n. comb. ( Malaysia)

14 Hind wing pads about 1/3 the length of metanotum; terminal filament about 2/5 the length of cerci............................................................................... L. borneoensis (Müller-Liebenau) n. comb. ( Malaysia)

- Hind wing pads slightly shorter than the length of metanotum; terminal filament about 3/5 the length of cerci.......................................................................... L. operosus (Müller-Liebenau) n. comb. ( Malaysia)