Spinaethorax tonoius (Palacios-Vargas & Sanchez , 1999) Palacios-Vargas & Sanchez, 1999

Papac, Vladimir & Palacios-Vargas, Jose G., 2016, A new genus of Neelidae (Collembola) from Mexican caves, ZooKeys 569, pp. 37-51 : 44-45

Taxon classification Animalia Collembola Neelidae

Spinaethorax tonoius (Palacios-Vargas & Sanchez, 1999) comb. n.

Note.

This species, described from a cave in State of Guerrero, shares with new type species of the genus similar generic characters like presence of sword-like macrosetae on oral fold, globular sensillum on Ant. III., stouter spines on Th., fusion of Ant. III and IV, 3+3 setae around Abd. s.f., 2+2 setae on proximal part of dens and absence of E3 spine on distal part of dens. The main differences consist in setation of hind Abd. (numerous thickened macrosetae in Spinaethorax tonoius comb. n. vs. numerous spine-like microsetae in Spinaethorax spinotricosus comb. n.), in chaetotaxy of the apex of head (only one spine IL 1 in Spinaethorax tonoius comb. n. vs. three spines IL 1-IL 3 in Spinaethorax spinotricosus comb. n.), in the structure of tenent hairs on Ti. (more developed in Spinaethorax tonoius comb. n. vs. shorter in Spinaethorax spinotricosus comb. n.) and in setation around Abds.f. (absence of axial spine in Spinaethorax tonoius comb. n. vs. presence of spine in Spinaethorax spinotricosus comb. n.). Species description is based only on one adult specimen (holotype) and does not allow us to describe it in an appropriate way, along with drawings and measurements.

Discussion.

The family Neelidae was for a long time an overlooked group of Collembola , mainly due to its small size and lack of diagnostic characters. In spite of the foregoing facts recent years molecular phylogenetic analysis have revealed unexpected diversity within this family ( Schneider et al. 2011). Recently Neelus has been revised ( Kováč and Papáč 2010) as well as Megalothorax with a redescription of the nominal species Megalothorax minimus (Schneider & D´Haese, 2013). Soon after additional new taxonomical characters in genus Megalothorax were defined ( Papáč and Kováč 2013). Spinaethorax spinotrichosus comb. n. and Spinaethorax tonoius comb. n. share many specific characters. These species were included in the genus Megalothorax (Palacios-Vargas & Sánchez, 1999), because some features (fusion of Ant. segments III and IV, absence of E3 spine on distal dens) indicated that those specimens belonged to this genus. On the other hand, some characters link those specimens to Neelus (dp with 2+2 setae - except Neelus fimbriatus , 1+1 neosminthuroid setae at the base of Abd. IV sternite). Schneider and D´Haese (2013) stated that chaetotaxy of Megalothorax spinotricosus clearly differs from the other Megalothorax by the presence of great number of microsetae on Abd. and pointed out that Megalothorax spinotricosus deserved its own genus. On the basis of recent diagnostic features, material of these two species was re-examined arriving to the same conclusion as Schneider and D´Haese (2013) that they represent a new genus in the Neelidae . Spinaethorax gen. n. differs from other genera by striking morphological features and combinations, which clearly separate them, e.g. sword-like macrosetae on oral fold, six setae on basomedian field of labium, Ant. III and IV fused, presence of small globular sensillum Sg on Ant. III, three marginal setae around abdominal sensory field, absence of spine E3 on dd and dp with two seate. For comparison with other genera see Table 4.