Oribatellidae, Jacot, 1925

Bayartogtokh, Badamdorj & Ermilov, Sergey G., 2019, Ontogeny of morphological traits in Oribatella palustris Hammer, 1962, with remarks on juveniles of Oribatellidae (Acari: Oribatida), Zootaxa 4717 (1), pp. 85-103 : 100-101

Key to known tritonymphs of Oribatellidae

1 All gastronotic setae straight or normally arched; seta da with normal structure.................................... 2

- Gastronotic seta da with specific structure, winding and twisted distally; other gastronotic setae normal....................................................................................... Ophidiotrichu s tectus ( Michael, 1884)

2 All gastronotic setae long, approximately same in length...................................................... 3

- Marginal setae on gastronotum long, but some of central setae short or minute..................................... 7

3 With 15 pairs of gastronotic setae........................................................................ 4

- With 13 pairs of setae (c 1, dm or dp absent)................................................................. 6

4 Body length not more than 440 µm; bothridial seta strongly barbed.............................................. 5

- Body length 522 µm; bothridial seta weakly barbed marginally........ Oribatella heatherae Behan-Pelletier & Walter, 2012

5 Gastronotic setae very long, strongly barbed; bothridial seta barbed throughout its length...................................................................................... Oribatella yukonensis Behan-Pelletier & Walter, 2012

- Gastronotic setae medium long, sparsely barbed; bothridial seta barbed only in distal half..................................................................................................... Oribatella berlesei ( Michael, 1898)

6 Setae c 1 and dm absent; bothridial seta very thin; nymphs do not carry exuvial scalps..... Oribatella calcarata ( Koch, 1835)

- Setae dm and dp absent; bothridial seta bacilliform, heavily barbed; nymphs carry exuvial scalps............................................................................................ Oribatella metzi Behan-Pelletier, 2011

7 Either c 1 or some setae of d -series minute, smooth........................................................... 8

- Gastronotic setae c 1 and some of d -series not minute, but distinctly shorter than other setae........................... 9

8 Setae dm and dp minute, c 1 long, barbed; bothridial seta long, extending beyond rostrum....................................................................................... Oribatella canadensis Behan-Pelletier & Eamer, 2010

- Setae c 1 minute, dm and dp short, smooth; bothridial seta short, not reaching rostrum......... Oribatella arctica Thor, 1930

9 Only seta c 1 distinctly shorter than other setae.............................................................. 10

- Not only c 1, but also some setae of d -series distinctly shorter than other setae..................................... 11

10 Bothridial seta short, clavate; gastronotic seta c 1 minutely barbed.................... Oribatella palustris Hammer, 1962

- Bothridial seta very long, setiform; gastronotic seta c 1 smooth...................... Oribatella sexdentata Berlese, 1916

11 All gastronotic setae setiform, tapered distally; anterior margin of gastronotum medially distinctly convex.............. 12

- All gastronotic setae broadened, not tapered distally; anterior margin of gastronotum medially not convex, but widely rounded.................................................................... Oribatella nortoni Behan-Pelletier, 2011

12 Bothridial seta very long, longer than le and in; setae c 1, da and dp distinctly shorter than other setae.......................................................................................... Oribatella superbula ( Berlese, 1904)

- Bothridial seta medium long, shorter than le and in; only setae c 1 and da distinctly shorter than other setae.................................................................................. Oribatella quadricornuta (Michael, 1880)