Scutisotoma

Huang, Cheng-Wang & Potapov, Mikhail, 2012, Taxonomy of the Proisotoma complex. IV. Notes on chaetotaxy of femur and description of new species of Scutisotoma and Weberacantha from Asia, Zootaxa 3333, pp. 38-49 : 41

Division of Scutisotoma to groups of species

Twenty six examined species of the genus can be classified to three species groups. In the proposed division the shape of maxillary palp and number of prelabral chaetae are decisive characters. Chaetotaxy of femur and Abd.V are used as additional characters since they are more influenced by the general polychaetosis of the body.

schisti group. Maxillary palp bifurcate. 4 prelabral chaetae. Ventral chaetae on thorax absent. Femur 1 with 3, more rarely 2 e- chaetae. Mucro bi- or tridentate, in latter case proximal tooth positioned more laterally. Length of furca varies. Chaetotaxy of Abd.V typical for the genus, unmodified. Most species of the genus belong to this group ( acorellata , ananevae , armeriae , baica , dodecocellata , karadagi , kolymica , ladaki , longisensilla , matalini , millimetrica , montana , muriphila , nicksmeti , schisti , stachanoremi , stepposa , tianshanica , tolerans , trichaetosa sp. nov.). Holarctic.

christianseni group. Maxillary palp simple. 4 prelabral chaetae. Ventral chaetae on thorax present or absent. Femur 1 with 3–4 e -chaetae. Mucro tridentate, proximal tooth positioned more laterally than apical and subapical teeth. Furca of medium length. Abd.V polychaetotic, with many thick chaetae ( Figs 7 , 15 in present paper; Fig. 10 B in Dunger 1982; Fig. 14 in Vilkamaa 1988). With four species ( bengei sp. nov., christianseni , fjellbergi , oirota Vilkamaa) distributed in inner areas of Asia.

subarctica group. Maxillary palp simple. 3 prelabral chaetae. Ventral chaetae on thorax absent. Femur 1 with 2 e -chaetae. Mucro tridentate, all three teeth positioned in a line. Furca of medium length. Abd.V with few chaetae. Three species ( indigirka , robustodens sp. nov., subarctica ). Palearctic.

Figures

FIGURES 7 – 14. Scutisotoma bengei sp. nov.: 7, posterior part of abdomen (chaetae of Abd. VI not shown); 8, position of sensilla on Abd. V, other individual; 9, PAO and ocelli; 10, chaetotaxy of Ant. 3; 11, apical part of Leg 3; 12, dens and mucro, lateral view; 13, furca, posterior view; 14, dens and mucro, anterior view.

FIGURES 15 – 18. Scutisotoma christianseni (15 – 17) and S. bengei sp. nov. (18): 15, posterior part of abdomen (chaetae of Abd. VI not shown); 16, dens and mucro, lateral view; 17 – 18, position of s and ms on Abd. III.