Endonura Cassagnau 1979

Endonura Cassagnau, 1979

Neanura (Endonura) Cassagnau, 1979: 192.

Type species: Achorutes tetrophtalmus Stach, 1929: 282.

Diagnosis. Collembola, Neanurinae, Neanurini. 0–2 + 0–2 eyes, pigmented or not. Colour of body blue or white, never yellow or red. Dorsal tubercles present, well developed. Mouth part reduced: maxilla styliform, mandible slender or rarely strong. Labrum chaetotaxy: 4/2, 4 or 0/2, 2. Sensilla S on ant. IV of similar size. Head with 10 or 12 tubercles. Tubercles Af and Cl separate or sometimes fused. Tubercles Di and De on head separate, sometimes Di not differentiated. Arrangement of chaetae Di and De on head of the uncross-type (Deharveng 1983). Tubercles L and So on head fused. S-chaetae present in typical arrangement and number; 22/11111 on each half tergite from th. II to abd. V. Abdomen IV with 8 tubercles: 2 Di, 2 De, 2 Dl and 2 L, or 5 tubercles: (Di+Di), 2 (De+Dl) and 2 L. Abdomen V with 3 tubercles: 2 (De+Dl+L) and (Di+Di) or 2 tubercles: 2 (Di+De+Dl+L). Tubercles Di on abd. V fused or separate. Cryptopygy absent or rarely present. Tibiotarsal chaetotaxy 19, 19, 18. Claw with inner tooth or untoothed.

Discussion. Till now, a definition of the genus Endonura was mainly based on the following characters: 0–2 + 0–2 eyes, reduced mouth part, the uncross-type of chaetotaxy on head, separate tubercles Di and De on head, 8 tubercles (2 Di, 2 De, 2 Dl, 2 L) on abdomen IV and 3 tubercles on abdomen V (tubercles Di fused). E. incolorata and E dudichi possess all mentioned characters except the number of tubercles on abdominal segments (in dudichi 5 tubercles: (Di+Di), 2 (De+Dl) and 2 L on abd. IV; in incolorata 2 tubercles (Di+De+Dl+L) on abd.V). However, the uniqueness of both characters does not seem to be a sufficient reason to erect a new genera, especially a monotypic one. Moreover, both mentioned species are closely related to Endonura tatricola and altogether form a group of species well separated morphologically from other members of the genus (see: Discussion of E. tatricola). In addition, their distribution is strictly limited to the Carpathians which were probably the centre of their origin. In the light of the facts presented above I decided to place E. incolorata and E dudichi within this genus and to modify its diagnosis accordingly.

Because of chaetotaxy and arrangement of tubercles on head, Endonura is most similar to the European genus Cryptonura Cassagnau, 1979. Nevertheless, they can be easily distinguished by the number of tubercles on abd.V (in Endonura two or three tubercles, in Cryptonura four tubercles). In addition, most species of Cryptonura are characterised by strong cryptopygy (in Endonura absent or weak developed) and massive mandibles (in Endonura rather thin).