New Nicoletiidae ( Zygentoma : Insecta ) from Brazil living in fire-ant ( Hymenoptera : Insecta ) nests

A new myrmecophilous silverfish (Zygentoma: Nicoletiidae: Subnicoletiinae) from Rio de Janeiro, Brazil, found living in fire ant (Solenopsis saevissima, Formicidae: Myrmicinae) nests is described: Allotrichotriura saevissima gen. nov. sp. nov. is compared with the other genera and subgenera known in the subfamily. The main diagnostic features would include the combination of body shape, body and head setation, morphology of praetarsus, and number of abdominal stylets and vesicles. Although further quests were attempted at the type-locality, only the original described material, exclusively composed of females, remains known.


INtRODuCtION
The fauna of the Nicoletiidae (Zygentoma) in Brazil remains largely unknown and currently includes 19 known species distributed in 11 genera, including leaf-litter and soil-dwelling (edaphic: ED), myrmecophilous (MY), termitophilous (TE -all living with Termitidae) species and species living with yet undetermined hosts (UH) or even in unknown biotopes (UB), as well as cave-dwellers (troglobites: TR).The Atelurinae, with 13 species are the most diverse group, being Grassiella (Atelurinae) so far the most diverse genus, with six Brazilian species of which five are endemic.
One new species solely represented by female specimens, belonging to a new genus of Subnicoletiinae was obtained from fire ant nests (Solenopsis saevissima, Formicidae: Myrmicinae) from Rio de Janeiro State.It is described below and the new genus is compared with the genera and subgenera in that subfamily.
Note 1: The validity of Nicoletia neotropicalis Silvestri, 1901 -MT (ED) (Silvestri, 1901b,c;Escherich, 1905) warrants investigation; the con-specificity of samples from Argentina, Brazil, Paraguay and Uruguay recorded under this name needs to be revised (they hardly pertain to Nicoletia, and they may not even belong to Nicoletiinae).Note 2: Nicoletia armata Silvestri, 1901 (ED), probably a Cubacubaninae in need of revision, was reported by Escherich (1905) to occur in Brazil: "…Silvestri fand sie in Brazilien, Uruguay und Paraguay…".In fact, this enigmatic species was registered by Silvestri (1901b,c) from Argentina, Paraguay (Paraná) and Uruguay, but never from Brazil.Note 3. We never studied this species but Espinasa (pers.comm.)believes that its description is incorrect and that it will be no more than Coletinia brasiliensis; so, the correct nomenclature of these species remains debatable, as it is the real occurrence of the Cubacubaninae in Brazil.

MAtERIAL AND MEtHODS
The studied material is deposited in the entomological collections of the Museu de Zoologia da Universidade de São Paulo, SP, Brazil (MZUSP) and of the IICT/JBT Zoologia, Lisbon, Portugal (CZ, the former Centro de Zoologia).Allotrichotriura were dissected under a stereomicroscope in ca 70-80% ethanol, being the dissected pieces directly mounted in "Tendeiro Liquid" and dried at 40°C for about one week (before observation) and for 2-3 weeks (before storage, until solidification); whole specimens remained alcohol-preserved.Observations and species identification were performed with a compound microscope and drawings made with camera-lucida.

RESuLtS AND DISCuSSION
Allotrichotriura gen.nov.
Description: Female: Nicoletiidae Subnicoletiinae of small body size (< 4 mm), ateluriform (short and stout), lacking pigment and without scales; most of the setae are thin and very short (only a few acute or apically slightly bifurcated macrochaetae exist on the head and tergites).Head exposed, setose.Nota, abdominal tergites and sternites, with setae arranged in several irregular rows.Incisive and molar areas of mandibles well developed.Galea and lacinia equally developed; galea with 1 apical conule only, the prostheca not clearly longer than the apical tooth of lacinia.Maxillary and labial palps typical.Praetarsus simple and complete.All abdominal segments exposed.Stylets on abdominal segments VI-IX (4 pairs), vesicular structures reduced to pseudovesicles VII.Subgenital plate widely elliptical, the ovipositor spindle-shaped, with thin setae only and clearly longer than level of stylets IX.Cerci and paracercum short, lacking spines.Male sex unknown.
Etymology: From the Greek, Allos: other, and from Trichotriura Silvestri, 1918, a West African genus probably quite close to the new endemic Brazilian genus.
Like the new genus, Hematelura (Escherich, 1906 andWygodzinsky, 1958b) and, mainly, Trichatelura Silvestri, 1932, Trichotriura Silvestri, 1918, Trichotriurella Mendes, 2002and Trichotriuroides Mendes et al., 1994 have, like the new genus, more or less "atelurid-shaped" bodies, round, short and broad, as well as a clear reduction of both, the number of abdominal stylets and vesicular structures; the last aforementioned four genera share with Allotrichotriura the single apical conule in the galea but they have stylets restricted to urosternites VII-IX (3 pairs only) or these structures can be even less numerous (one pair only in Trichotriurella).
Furthermore, Trichatelura, ecitophilous and Neotropical, with 2 known species from Brazil, has a single row of strong setae along the posterior border of the urotergites, thin and cylindrical labial palp apical article, very different subgenital plate, and a much shorter ovipositor.In the new genus all tergal and sternal setae are similarly developed, thin, short and arranged in several irregular rows, being slightly more dense and more developed on posterolateral areas only, with just a single macrochaeta postero-laterally.Trichotriura, termitophilous from Nigeria, with even smaller specimens, shows, like the preceding genus, different dorsal setation, urotergites provided with just one posterior row of well-developed setae; furthermore, the distal article of labial palp is also almost sub-cylindrical.
Trichotriuroides, monotypical and endemic to the Equatorial Guinean island of Bioko (formerly Macias Nguema, before that Fernando Poo) seems more similar to Allotrichotriura though the comparison remains difficult as the type-series of the new genus includes exclusively females while Trichotriuroides remains known from a single male.Main differences seem to concern the almost completely concealed abdominal tergite I due to the proportional development of the thorax (free in the new genus), the cylindrical labial palp distal article (oval in Allotrichotriura), the distinct empodium, the density of setae along the body (mainly nota) and the lack of thoracic macrochaetae.
Trichotriurella, from the former Zaire and also monotypical, with mature specimens also smaller than those of the new genus is similarly known from FIGuRES 14-17 : Allotrichotriura saevissima gen.nov.sp.nov., female.14.Urosternites I-III.15.Urosternite V. 16.Urosternite VI. 17. Urosternite VII and subgenital plate.Scale bars: 0.1 mm.females only; among other dissimilarities, there is different cephalic setation, very distinct mandibles and maxillae, longer antennae and only one pair of abdominal stylets.
Hematelura, from Africa with one only representative (autochthonous?) in Brazil, shows (at least in the Afrotropical species we could study) two well developed conules on the galea.This genus presents some variability in the number of abdominal stylets and vesicles, and the 3 known species that completely lack scales, H. convivens Escherich, 1906, H. setosa (Silvestri, 1918  with the remaining species and if correctly characterized, has vesicular structures on the abdominal segments VI-VII in contrast to all the remaining Hematelura and to the condition in Allotrichitriura gen.nov.; furthermore, the ovipositor is much longer than in the new Neotropical genus.H. setosa, known exclusively from type material from Guinea, with 5 pairs of stylets (V-IX), is the only species to present (in males) a conspicuous projection on the antennal pedicellus; as a rule in the known females, the ovipositor is much longer than in the new genus; lastly, H. delamarei, from the Ivory Coast, known only by its 5 mm long male holotype, also with 5 pairs of abdominal stylets, shows a distinct, acicular empodium and peculiar, scattered, delicate, lanceolate setae on the urotergites (nothing similar occurs in the new genus).Description: Female: Body length: 3-3.2 mm; thorax length: 1.4 mm; thorax width: 1.4 mm; maximum measured length of antennae: 1.3 mm; cerci length: 0.9 mm; terminal filament short, always damaged.Hypodermal pigment absent; setae and macrochaetae hyaline.Head (Fig. 1) wider than long, the cephalic capsule with numerous thin short setae and with a few frontal acute macrochaetae.Antennae short, without peculiar features.Incisive and molar areas of mandible well developed (Fig. 2).Maxillae without remarkable features, the prostheca slightly longer than the apical tooth of lacinia, as long as the galea, which has only one reduced apical conule (Fig. 3).Maxillary palp delicate the distal article cylindrical and longer than the previous one, and with several apical sensilla (Figs. 4,5).Labium as usual, the labial palp (Fig. 6) medium-size, its distal article ovoid, ca.1.2 times longer than wide and with six typical apical papillae.

Allotrichotelura saevissima
Nota short and wide, with numerous irregular rows of minute thin setae, their posterior border almost straight (pronotum) to slightly concave (metanotum); only one very short, apically bifid macrochaeta, stronger though not longer than the usual setae, occurs on the anterior-lateral angle of pronotum (Fig. 7).Legs typical, tibias (Figs. 8, 9) ca 3 times longer than wide, the empodium simple and complete (Fig. 10).
Urotergites I-VIII like the nota, with several thin short setae, more numerous on the infralateral area; one only stout macrochaeta present (Fig. 11), its robustness increasing from the anterior to the posterior segments; infralateral areas of urotergite IX poorly extended, as in Fig. 12. Urotergite X sub-trapezoidal (Fig. 13), much shorter than wide at base, its posterior notch obtuse, not especially depressed; 1+1 infralateral plus 1+1 shorter lateral macrochaetae on the posterior border and a few thin discal setae.
Urosternite I almost glabrous with a few submedian setae, II with 1+1 lateral plus 1 median well delimited groups of setae (Fig. 14); abdominal sternites III-VII with abundant thin small setae, uniformly distributed, like the dorsal plates (Fig. 15).Four pairs of abdominal stylets, on segments VI-IX (Fig. 16); only pseudovesicles VII are present.Posterior border of urosternite VII clearly concave the subgenital plate wide and short, parabolic to almost triangular (Fig. 17).Coxites VIII and IX typical (Fig. 18); ovipositor spindle-shaped, clearly exceeding the apex of stylet IX; gonapophyses VIII and IX as in Figs. 19, 20 with ca 6 divisions.
Terminal filaments short, without special features.
Male unknown.

Etymology:
The new species is named after to its known ant host species in Brazil, Solenopsis saevissima.