Cyphoderus Nicolet, 1842

Jantarit, Sopark, Satasook, Chutamas & Deharveng, Louis, 2014, Cyphoderus (Cyphoderidae) as a major component of collembolan cave fauna in Thailand, with description of two new species, ZooKeys 368, pp. 1-21 : 4-5

Cyphoderus Nicolet, 1842

Type species.

Cyphoderus albinus Nicolet, 1842

Character assessment.

Several characters of taxonomic importance were discovered or re-appraised in the course of this study.

1)

All antennal segments were examined on both dorsal and ventral sides, revealing 10 types of chaetae (Fig. 3A). Their distribution pattern on the antennae is complex, but similar in the two species. Similarities are also obvious with the few Entomobryoidea where antennal chaetotaxy has been described. For instance, sens 1 to 5 and 8 of AIIIO as figured in Sinella by Chen and Christiansen (1993) were easily retrieved in our Cyphoderus (Fig. 3G). Several of the chaetal types recognized here are also found in other genera of Entomobryoidea . However, patterns are very complex and their comparisons would require detailed analyses beyond the scope of this paper.

2)

S-chaetae can be grouped in four types (Fig. 4A), with chaeta S4 difficult to distinguish from type-5 mes. The S-chaetae formula observed in our species, as well as in other unidentified ones of the bidenticulati group, is 0/2,1/1,2,3,4,3,0 from head to Abd.VI (Figs 4-6), including 0/1,0/1,0,1,0,0 for S1; 0/1,1/0,1,0,0,0 for S2, 0/0,0/0,1,2,2,3 for S3 and 0/0,0/0,0,0,2,0 for S4. This S-chaetae pattern is similar to that of Entomobryoidea , except for the position of chaetae S1 and S2 on Th.II. In Entomobryoidea , S1 and S2 (=ms and S in Zhang et al. 2009) are close each other antero-laterally on the tergite (see Zhang et al. 2009). In the examined Cyphoderus , S2 is not close to S1, but intermediate between the position of antero-lateral S2 and of the postero-lateral S2 as observed in several Entomobryidae .

3)

Pseudopores on tergites are arranged as in the Entomobryoidea species where they have been recorded ( Jordana 2012 for instance): 1,1/1,1,1,1,0,0 from Th.II to Abd.VI. The presence of dorso-distal pseudopores on manubrium (2+2 in the studied Cyphoderus , Fig. 7H, 8D) is also characteristic of Entomobryoidea . Special to Cyphoderus described here are the 2+2 pseudopores behind the posterior row of chaetae of Abd.IV, found also in other unidentified Cyphoderus of the bidenticulati group (Fig. 4B). This pseudopore location is only known in Troglopedetinae , i.e., in Troglopedetes ( Deharveng 1988), in Cyphoderopsis (Jantarit et al. 2013) and in Trogolaphysa ( Soto-Adames and Taylor 2013), with a number of pseudopores different for each genus. A ventral pseudopore is present on antennal area, in the same location as in Isotomidae ( Deharveng 1979), Neanuridae ( Deharveng 1983) and Onychiuridae (Pomorski 1998, Martinez et al. 2004). At least, the presence of 1+1 or 2+2 pseudopores on head anteriorly to the antenno-basal line (Fig. 2H) is a new pseudopore location for Collembola , unnoticed as far as we know in other genera of the class.

4)

Important features of dorsal head chaetotaxy have been discovered by Yoshii (1980, 1987, 1992), useful for characterizing the family Cyphoderidae and several taxa of lower rank. The number and arrangement of post-labial chaetae as well as the presence of one mic among them are the same in the two species described here. However, they differ when compared with other species and might provide another promising set of taxonomic characters.

5)

Body chaetae of various types were detected and tentatively grouped in categories. The mes of type-5 are the most numerous chaetae dorsally. They are seen as smooth under microscope examination, but serrated under SEM, Fig. 4A5; distinguishing them from S4 sens is especially difficult on Abd.IV where both are present, and the same confusion may arise for many other Entomobryoidea . As patterns of these mes as well as those of S4 sens seem to be stable inside population and different between species, further investigations will have to re-examine this character for its use in taxonomy.

6)

The chaetotaxy of dorsal side (Figs 4-6) matches in most cases that given by Szeptycki (1979) for Cyphoderus albinus , and is very similar to that of Entomobryoidea (see Zhang et al. 2009). Main differences include the relative position of S1 and S2 on Th.II (see above), and chaeta “as” of Th.III as a mes in our material versus a short S-chaetae in Szeptycki (1979).

7)

One of the most important characters for differentiating species of the bidenticulati group is claw morphology, and it is the most diagnostic feature of the species described here. Although some variability in size and position of the various dental teeth has been noticed by other authors, it has not been taken into account in previous descriptions, leaving doubts about the validity of several species.