Stachorutes cabagnerensis n . sp . , Collembola ( Neanuridae ) from Central Spain , and a preliminary approach to phylogeny of genus

Stachorutes cabagnerensis n. sp., Collembola (Neanuridae) from Central Spain, and a preliminary approach to phylogeny of genus.— A new species of the genus Stachorutes, Stachorutes cabagnerensis n. sp., from central Spain is described. It is characterized by the presence of 6+6 eyes in the head, retinaculum 2+2 teeth, dentes with 5 hairs, and the absence of mucron. A phylogenetic analysis of this genus was attempted. Potential synapomorphies supporting the monophyly of Stachorutes are presented. One member of the genus (the Nearctic S. navajellus) appears as a basal form, phylogenetically distant from the remaining (Old World) species. There is evidence for a monophyletic infrageneric clade with the species S. dematteisi, S. jizuensis and S. sphagnophilus. However, more information is required for further phylogenetic resolution.


Introduction
The genus Stachorutes was established by Dallai (Dallai, 1973) from Italian specimens from the province of Canzo, according to the type species Stachorutes dematteisi.Dallai characterized it for its small Antenna IV with simple sensillae, jaw with two teeth, simple maxillae, 2+2 eyes disposed as in the genus Micranurida, postantennal organ present, claw without empodial appendage, tenent hairs absent, reticulum and furca present, and without anal spines.Deharveng & Lienhard (1983) established two new species taken from the Eastern French Pyrenees and the Swiss Alps, and re-defined the genus.A further re-definition was later proposed by Jordana et al. (1997) in their monograph on Iberian Collembola.Thibaud & Palacios-Vargas (2000) added new characters, which resulted in an even sharper definition of the genus.A summary of the morphological features of potential use for defining Stachorutes is given in table 1.
At present, Stachorutes Dallai consists of 16 species distributed all around the world.Eight species occur in Europe: S. cabagnerensis n. sp.; S. dematteisi Dallai, 1973; S. longirostris Deharveng & Lienhard, 1983; S. ruseki Kovac,1999; S. scherae Deharveng & Lienhard, 1983, S. sphagnophilus Slawaska, 1996; S. tatricus Smolis & Skarzynski 2001(Smolis & Skarzynski, 2001), S. valdeaibarensis Arbea & Jordana, 1991.One species is known from Africa (S. dallai Weiner and Najt, 1998), three from North America: S. escobarae (Palacios-Vargas, 1990), S. maya Thibaud &Palacios-Vargas, 2000 andS. navajellus Fjellberg, 1994 and four in Asia: S. ashrafi (Yosii, 1966), S. jizuensis Tamura and Zhao, 1997;S. tieni Pomorski &Smolis, 1999 andS. triocelatus Pomorski &Smolis, 1999.The primary purpose of the present study was to describe a new taxon, S. cabagnerensis n. sp.However, since no attempt has currently been directed either at testing the monophyly of the genus, or at resolving its internal relationships, a preliminary approach to these questions was attempted.This task was complicated by the generally low degree of phylogenetic resolution of the group.However, given the small number of species, and the lack of information on the majority of them, any insight into the problem may help in facilitating taxa and character selection for further phylogenetic studies on pseudachorutine springtails.

The new species of Stachorutes
Soil samples were taken following the standard method designed for the research project "Bioasses".An area of 1 km 2 was chosen in each selected land unit and a sample was taken every 200 m.A total of 16 units was prospected, each consisting of six spots representing different stages in development of the vegetation.In Spain, the National Park of Cabañeros was chosen and di-vided into six different units.In each of them, samples were collected according to the method designed.Individuals belonging to the genus Stachorutes were obtained in wooded units only.These locations were: Unit 1. Natural wood with vegetation of holly oaks Quercus ilex ilex L., oaks Quercus pyrenaica Wild.and cork oaks Quercus suber L., with undergrowth of cistus Cistus ladanifer L., heather Erica australis L. and Erica arborea L., arbutus Arbutus unedo L., located in the province of Ciudad Real in Navas de Estenas, UTM: 30SVJ5754.Samples 106-H, fallen leaves from holly oak, with heather and moss, nine specimens.Unit 2. Reforestation pinewood, Pinus pinaster Aiton, also in the province of Ciudad Real, in Horcajo de los Montes, UTM: 30SVJ6973.Sample 204-H 2, fallen pine leaves after second year, three specimens.Sample 207-H, fallen pine leaves, two specimens.All samples were taken during the months of April and May (2001), a period characterised by a seasonal maximum in the numbers of both individuals and species (Simón, unpubl.data).

Cladistic analysis
The data matrix was analysed using the program Henning 86 (Farris, 1988; options h*, mh* and bb*), treating all multistate characters as unordered.As an alternative exploratory option, the successive weighting approach (Farris, 1969(Farris, , 1989) ) was attempted with the same programme.All other analyses, as well as character state optimisation, were completed through Winclada (Nixon, 2002) and Nona (Goloboff, 1993) (strict, majority consensuses, as well as bootstrap and jacknife tests with 100 replicates).Since the number of species currently included in Stachorutes is low, an effort was made to include all of them in the analyses.This resulted in two problems related to the character state coding (see character list below): First, only partial information from S. ashrafi was available, and as many as 5 of the 13 characters were coded as unknown.Second, character 12 was found to be variable among individuals of S. longirostris from Pyrenean samples.Given the inability of the cladistic packages used in this study to make a different treatment of unknown vs. non comparable character states, this species was entered as four different taxa (a,b,c,d).We believe that these decisions may be acceptable given the prospective nature of our approach.

Description
Stachorutes cabagnerensis n. sp.Length of 0.66 mm in adult/s and 0.44 mm in young, dark blue in the adult/s, and light blue in the juveniles.Dorsal setae reduced, subequal, with sensillae longer and thicker than in normal hairs.Integument with thickly grained surface.
Reduced mouth parts, jaw with 4 teeth, maxilla styli form with two teeth,one ending in two apical teeth and the other in a hook with 5-6 teeth along the apical area.Labium without hair L, its relation with the length of the nail is 3 ( fig. 2).Ocular spot with 6 eyes, 3 anterior (A, B, C) and 3 posterior (E, F, G), the H and D are lacking (fig.4).
Oval post antennal organ with 13 to 15 vesicles similar in size, disposed in one line, twice longer than the nearest corneola and with approximately the same diameter (fig.4).
Antenna quite thick, the relation with the head diameter is 0.54 in adults and 0.58 in juveniles.Antenna I with 7 hairs, II with 12, III and IV are joined dorsally; segment III shows about 17 hairs and a sensorial organ formed by two microsensilla (si) as a war club and long thick lateral sensilla: (sgd) and (sgv) and an extra ventral microsensilla (sa).Antenna IV with normal hairs, straight, some small, without sensorial hair-brush in the ventral area.With 6 olfactory sensilla, 4 in the dorsal area (S1 to S4) forming a rhomb, and 2 in the ventro-apical area (S7, S8).Furthermore, there is a dorsal external microsensilla (m) and a very small distal organ.An apical tri-lobed vesicle is located at the apex of the antenna (fig.5).
Claw without teeth and empodial appendage.
Genital orifice in the male with 18 hairs, in the female with 8 hairs in the anterior margin of the genital orifice, plus two central ones.

Discussion
The new species shows 6+6 eyes like two other species of this genus, ruseki Kovac, 1999 from Slovakia and ashrafi (Yosii, 1966) from Nepal.This latter species may however not belong to this genus because of the number of olfactory Table 1.Anatomical features of potential use in the definition of the genus Stachorutes, as stated by different authors (+ feature present; -feature absent): A. Dallai, 1973;B. Deharveng & Lienhard, 1983;C. Jordana et al., 1997;D. Thibaud & Palacios-Vargas, 2000.Note that some of these characters display no variation within Stachorutes, and were not coded for phylogenetic analyses.

Figs
Table 3. Performances of the characters 1-13 in the initial parsimony analysis (above; characters unordered, without weight), and in the strict consensus derived from these trees (below).The figures given are the number of steps in the tree, consistency index (CI) and retention index (RI).

Conclusions
Although the overall resolution of the cladograms is low, a few points can be highlighted: (1) from a parsimonious point of view, the anatomical information currently available does not permit a detailed, highly resolved, phylogenetic hypothesis.This could only be solved by adding new characters; (2) some partial conclusions may be of interest for further studies: 1.The monophyly of the group can be provisionally supported on the basis of two synapomorphies (fig.7, characters 0 and 4: jaw with 3 teeth, and five ocelli present).This interpretation requires further assessment as there is no out-group taxon to polarise character state changes at the basal node (i.e., external to Stachorutes + Pseudachorutes).Characters 2, 5, 8 and 12 support the monophyly of an infrageneric clade including all the other members considered in this study except navajellus.
2. The position of navajellus is peculiar for it apparently belongs to an isolated basal group or,it may have lost some features of the rest of the group due to reversal in characters 2, 5 , 8 and 12.
3. Within the ingroup, the resolution of the consensus is low.Only one clade with three species (dematteisi, jizuensis y sphagnophilus) can be defined with some accuracy, and even so, on the basis of one single nonhomoplasic synapomorphy (character 11, state 4).There is some evidence for the existence of two or three additional clades, but this is supported by homoplastic features only.
The combination of the inferred phylogenetic information (e.g., fig.10) and the known geographic distributions of the species dealt with here results in strikingly broad geographic ranges at the supraspecific clades, in contrast with rather local specific distributions.Thus, for instance, the clade comprising S. tatricus, S. ashrafi and S. ruseki could be classified as of wide Palaearctic distribution (or Eurasian, e.g.Cox, 2001;Morrone, 2002), ranging from Western Europe to the Himalayas (Yosii, 1966;Smolis & Skarzynski, 2001).The clade comprising S. longirostris and S. tieni includes species of the Western Palaearctic, Nearctic, and Oriental regions.The three species represented in the best supported clade (S. dematteisi + S. jizuensis + S. sphagnophilus) were described from Central Europe, Italy, and the Yunnan region in South-Western China.The closest relatives of these three taxa include one East African and one Nearctic member (Dallai, 1973;Palacios-Vargas, 1990), together with the new species S. cabagnerensis for Spain.A highly conservative interpretation of such patterns is recommended.Moreover, the authors' feeling is that either (a) very little insight on the phylogeny of the group has actually been gained, (b) the distributions of these springtail species are still very poorly known, or (c) an important number of related collembolan species in each of the main geographic areas mentioned have not yet been described.It is quite likely that all three hypotheses are equally pertinent.
A matrix of 13 characters (8 binary and 5 multistate) was prepared (table 2).The state 0 corresponds to the plesiomorphic character state.Rooting was done with reference to Pseudachorutes parvulusBörner, 1901.