A new species of Seira ( Collembola : Entomobryidae : Seirini ) from Northern Brazil , with the addition of new chaetotaxic characters

Seira caerucinerea sp. nov., a new species of springtail from the Cerrado domain, state of Tocantins, Brazil, is described and illustrated. The new species is mainly characterized by bluish-gray coloration and dorsal chaetotaxy presenting macrochaeta S7 on head, three macrochaetae (a6, m6 and p6) on margin of metathorax and 4+4 macrochaetae (a1, m2, m3 and m4i) on abdomen I. Characteristics of maxillary and labial papillae, chaetotaxy of subcoxae, collophore, ventral region of head, ventral and lateral region of abdomen IV and V, which are usually omitted in species descriptions within the genus, are also provided. This is the first species of Seira described from the Cerrado domain, as well as the first record of the genus from the state of Tocantins.

Seira Lubbock, 1870 includes epiedaphic springtails found mostly in litter, from low vegetation to canopy and over uncovered top soils, primarily in tropical landscapes (CHRISTIANSEN & BELLINGER 2000).It is the fourth most diverse genus of Entomobryidae and the most diverse taxon among the Seirini, comprising around 200 described species worldwide (BELLINGER et al. 2014).In the Americas 60 species of the genus have been recorded (CHRISTIANSEN & BELLINGER 2000), half of them from Brazil, mostly from the Northeastern Region of the country (GODEIRO & BELLINI 2014).From the Northern Region of Brazil, only S. nigrans (Arlé, 1959) and S. xinguensis (Arlé, 1959) were recorded until now (GODEIRO & BELLINI 2014, CIPOLA et al. 2014).
The closest genus to Seira is possibly Tyrannoseira Bellini & Zeppelini, 2011, and both taxa share similar mucronal morphology, overall dorsal chaetotaxy, and habitus.On the other hand, Seira presents a more variable dorsal chaetotaxy, with macrochaetae M1 and M2 present or absent on head; first abdominal segment with or without macrochaetae (absent in Tyrannoseira); and the first pair of legs of males devoid of any clear dimorphic structures (BELLINI & ZEPPELINI 2011).
Herein we present a new species of Neotropical Seira from the Cerrado Phytogeographic Domain, state of Tocantins, Northern Region of Brazil.The description also presents some data usually omitted in descriptions for the genus.

MATERIAL AND METHODS
The specimens were collected from leaf litter, preserved in 80% ethanol, clarified with potassium dichromate (K 2 Cr 2 O 7 ) and hydrochloric acid (HCl), and mounted on glass slides with Hoyer medium following the procedures described by ARLÉ & MENDONÇA (1982) and CHRISTIANSEN & BELLINGER (1998).One specimen was photographed in ethanol gel using a stereomicroscope (M165C) attached to a DFC420 digital camera.Photographs were digitally corrected using Leica Application Suite V3.4.1.The general chaetotaxy system used in the descriptions follows JACQUEMART (1974) modified by CHRISTIANSEN & BELLINGER (2000); labial chaetotaxy follows FJELLBERG (1999); maxillary palp follows MARI MUTT (1986); and detailed dorsal chaetotaxy follows SZEPTYCKI (1979) and SOTO-ADAMES (2008).Symbols used to depict the chaetotaxy are: large empty circles refer to macrochaetae; small empty circles to mesochaetae; small black circles to microchaetae; large empty circles with a small black dot inside to micro or macrochaetae; line over circles to chaeta present or absent; large black circles with two cross lines to pseudopores; two cross lines to scales; small curved seta to microsensillum; long multiciliated setae to bothriotricum; and triangle near bothriotricum to fan-shaped microchaetae.The material examined is deposited in the Invertebrate Collection of the Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus.
Etymology.The name "caerucinerea" refers to the blue to gray color of the new species (from Latin: caeruleo and cinereo).
Distribution and habitat.The species was so far only found in its type locality at the state of Tocantins, Brazil.Good's biogeographic zone 27 of the Neotropical region, Highlands of Eastern Brazil: North Brazilian (GOOD 1974).The climate of the area, according to the Köppen-Geiger system, is tropical (Aw) with predominance of the dry season (KOTTEK et al. 2006).This is the first species of Seira described from the Cerrado domain, as well as the first record of the genus from the state of Tocantins.
Remarks.The dorsal pattern of chaetotaxy in Seira caerucinerea sp.nov.resembles S. insalahi Jacquemart, 1974 from Algeria, north Africa, and S. paraibensis Bellini & Zeppelini, 2009 from northeastern Brazil.The new species differs from the others by its dorsal head chaetotaxy, which presents seta S4 as macro or microchaeta, and by the presence of interocular (p) macrochaeta (absent in S. insalahi and S. paraibensis) (Figs 21,23).Seira caerucinerea sp.nov.also presents a very peculiar dorsal chaetotaxy on mesothorax, with six macrochaetae in " PmA" group (p1,p1i,p1p,p1ip,p1i2 and p1i2p), whereas there are five in S. paraibensis and seven in S. insalahi; metathorax with three macrochaetae (a6, m6 and p6) in the lateral margin of tergite; abdominal segment I with four macrochaetae (a1, m2, m3 and m4i); and abdominal segment IV with 25 to 29 macrochaetae (E4p2, Ee10, F2p and F3p present  In addition to these characteristics, S. caerucinerea sp.nov.can be distinguished from S. paraibensis by the shape of unguiculi, which is acuminate with serrate edges in the new species and truncate with smooth edges in S. paraibensis (see BELLINI & ZEPPELINI 2009).Also, S. caerucinerea sp.nov. is the only one that presents a smooth seta in metaungues .Finally, both species present very distinct color patterns.

DISCUSSION
The chaetotaxic characteristics added in the description of S. caerucinerea sp.nov.are usually omitted in descriptions of Seira species and most other Entomobryoidea (ventral head chaetotaxy, prelabral and labral setae, labial papilla setae, maxillary palp setae, chaetotaxy of subcoxae and collophore, lateral and ventral region of the abdominal segments IV and V).These added characteristics provide new directions and features to compare species in the genus and in higher taxa.It is possible that some of these characters can also provide phylogenetic information, since they are stable within the genus, or even within Seirini.For instance, the prelabral and labral setae formulae described for S. caerucinerea sp.nov.(Fig. 4) can also be observed in S. urbana Nguyen, 2001, S. desapercebida Soto-Adames, 2002, S. dinizi da Gama, 1888and S. taeniata (Handschin, 1925) (see YOSII 1990: 536).Other examples are the five proximal smooth setae and five (A-E) labial papillae (Fig. 6), which are invariant in Seira and among the genera of Entomobryidae (CHRISTIANSEN & BELLINGER 1998, FJELLBERG 1999, XU et al. 2013).These features were also similarly described for S. socotrae Barra, 2004 and S. vanharteni Barra, 2004(see BARRA 2004: 404, 406).
Furthermore, other features vary among Seira species or at least among the Entomobryidae genera.The chaetotaxy of collophore can be quite variable in species of Seira and other Entomobryidae (YOSII 1990, BARRA 2004, 2010).However, species like S. iricolor Yosii &Ashraf, 1964, S. oligoseta Lee &Park, 1989, andS. vanharteni have a somewhat similar pattern to S. caerucinerea sp.nov.(Fig. 18).The chaetotaxy of the maxillary palp and subcoxae were described for other Entomobryidae genera, such as Acrocyrtus, Lepidocyrtus and Pseudosinella (MARI MUTT 1986, XU et al. 2013) and are more stable, especially the first characteristic (Fig. 7).Nevertheless, small differences can be detected among the few descriptions that provide such information.The stability of this particular morphological characteristic can only be proven by means of a revision of the already described species.The ventral chaetotaxy of the head has rarely been described.Only S. desapercebida (see SOTO-ADAMES 2002: 96) and S. caerucinerea sp.nov.descriptions provide this information among Neotropical Seira (Fig. 10).This character varies greatly among Entomobryoidea species, but the comparison between the new species and S. desapercebida shows some similar (and possibly stable) groups of setae.
Finally, the lateral and ventral chaetotaxy of the abdominal segments IV and V of S. caerucinerea sp.nov.are described here for the first time for Entomobryoidea (Figs 30,31,33).Even if these features are difficult to visualize, they can provide important elements and bring new insights into species comparisons of Seira and other Entomobryoidea.New descriptions and revisions will possibly support this point of view and the viability of comparing these taxonomic features.