Bagnallella biseta (Rapoport, 1963) Potapov & Deharveng & Janion-Scheepers, 2021

Potapov, Mikhail, Deharveng, Louis & Janion-Scheepers, Charlene, 2021, Taxonomy of the Proisotoma complex. VI. Rediscovery of the genus Bagnallella Salmon, 1951 and epitoky in Bagnallella davidi (Barra, 2001), comb. nov. from South Africa, ZooKeys 1072, pp. 185-204 : 185

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Bagnallella biseta (Rapoport, 1963)

comb. nov.

Bagnallella biseta (Rapoport, 1963) comb. nov.

Proisotoma biseta Rapoport, 1963

Material examined.

Adult male from Argentina under label " Tucuman, 19/4/59, entre maderas ...", deposited in the Museum national d’Histoire naturelle (MNHN), Paris, France. This individual was obviously among the material the original description was based on by E.H. Rapoport.


Maxillary palp bifurcate, four prelabral chaetae. Dens with ~50 anterior chaetae. Mucro bidentate. Anterior side of manubrium with 3+3 chaetae. 33/22235 s and 11/111 ms on body. Ventral chaetae absent on Th.III.


Maxillary outer lobe with four sublobal hairs, maxillary palp bifurcate. Labral formula as 4/5,5,4. Guard chaeta e7 present on labium. Ant. III without bms and with five distal s (including one lateral), without additional s-chaetae. Th. I, II, and III without ventral chaetae. S-formula as 33/22235 (s), 11/111 (ms). Tibiotarsal tenent chaetae (1,1,1) clearly clavate. Tibiotarsi 1-2 with more than 24 chaetae. Ventral tube with 6+5 chaetae (in the adult male studied). Retinaculum with 4+4 teeth and two chaetae. Dens long and slender, with numerous crenulations, many (~50) anterior and 17 (in the adult male studied) posterior chaetae. Anterior side of manubrium with 3+3 chaetae. Mucro bidentate.


Our redescription is based on one individual of E. Rapoport, and more material is needed to complete the understanding of B. biseta . The species obviously belongs to the genus Bagnallella by separation of two last abdominal segments and s-chaetotaxy of Abd.IV and V. After chaetotaxy of tibiotarsi, ventral tube, and dens, B. biseta appears to be a more polychaetotic species than its congeners. The close relation of B. biseta and B. tenella (sharing 3+3 manubrial chaetae) is doubtful due to difference in maxillary palp (bifurcate vs simple). The independence of B. koepckei and B. paronai from B. biseta call for further verification. Bagnallella paronai is not included in the key due to the incomplete diagnosis.


Argentina and Chile (see Mari Mutt and Bellinger 1990 for details).












Bagnallella biseta (Rapoport, 1963)

Potapov, Mikhail, Deharveng, Louis & Janion-Scheepers, Charlene 2021

Proisotoma biseta

Potapov & Deharveng & Janion-Scheepers 2021