Seira bicolorcornuta

Bellini, Bruno Cavalcante, Pais, Alexandra Peregrino & Zeppelini, Douglas, 2009, A new species of Seira Lubbock (Collembola: Entomobryidae) from Brazil with sexually dimorphic legs, Zootaxa 2080, pp. 38-46: 40-45

publication ID

http://doi.org/ 10.5281/zenodo.187336

persistent identifier

http://treatment.plazi.org/id/03F92F5B-FFDF-FFB0-93DD-FDAF2E4BFC7E

treatment provided by

Plazi

scientific name

Seira bicolorcornuta
status

sp. nov.

Seira bicolorcornuta  sp. nov.

( Figs. 2View FIGURE 2, 3View FIGURE 3, 4View FIGURE 4)

Type material. Holotype male, Brazil, Pernambuco, Alto do Moura , 7-ix-2007. Pais, A. coll  . Paratypes 7 females, Brazil, Pernambuco, Alto do Moura, 7-ix-2007. Pais, A. coll. Material deposited in the Museu Nacional, Rio de Janeiro ( CM/ MNRJ)  .

Description. Total length of the holotype 1,45 mm, other measurements are listed in Table 1. Habitus typically entomobryid ( Fig. 3 AView FIGURE 3). Colour of fixed specimens dark blue, with yellowish legs and yellowish antennae with dark blue pigment on the distal half of second, third and fourth segments ( Fig. 2View FIGURE 2). Colour of mounted specimens dark blue, with light blue pigment covering the antennae and furca. Yellowish rounded scales covering the first antennal segment, head, meso and metathorax, abdomen, coxae, trochantera, femora and tibiotarsus, manubrium and dentes. Fourth antennal segment not annulated, with an apical bulb and no pin setae ( Fig. 3 BView FIGURE 3). Eye patches oval, with the largest lens being B and the smallest lens being H, with four interocular feathered setae ( Fig. 3 CView FIGURE 3). Pre-labral and labral setae feathered. Labial triangle seta r reduced. M1, M2 and E feathered ( Fig. 3 DView FIGURE 3). Femora of the first legs slightly broadened in males, bearing eight setae modified into strong spines ( Fig. 3 EView FIGURE 3). One row with nine setae modified into spines on tibiotarsus ( Fig. 3 FView FIGURE 3). Trochanteral organ in V-shape with 19 spine-like setae ( Fig. 3 GView FIGURE 3). Pro, meso and meta ungues with four inner teeth, one pair at the base and two unpaired teeth at the apex ( Figs. 3 H, 3 IView FIGURE 3). Unguiculi acuminate, with slightly smooth edges ( Figs. 3 H, 3 IView FIGURE 3). Tenent hair capitate with slightly serrated edges. Venter of manubrium with seven subapical setae. No spine-like setae present on the manubrium. Mucro typically falcate ( Fig. 3 JView FIGURE 3) Dorsal macrochaetal distribution on head and body as in Fig. 4View FIGURE 4. Other characteristics are listed in Table 2.

Remarks. S. bicolorcornuta  sp. nov. resembles S. raptora  in many characters. The cephalic regions 2, 3, 4B and 4C have the same chaetotaxy in both species and the arrangement of the most anterior row of macrochaetae in region 1 is similar to some extent ( Fig. 4View FIGURE 4). Meso and metathorax have many similarities in regions 1B and 3 of mesothorax ( Fig. 4View FIGURE 4). In both species there are no macrochaetae on the first abdominal segment ( Fig. 4View FIGURE 4), an unusual condition in New World Seira  species. Along with these two species, only S. mirianae Arlé & Guimarães  and S. andensis Jacquemart  share this state in the Americas ( Christiansen & Bellinger 2000, Zeppelini & Bellini 2006). S. bicolorcornuta  sp. nov. and S. raptora  also have similarities on the chaetotaxy of abdominal segments III and IV ( Fig. 4View FIGURE 4). The species have the same pattern of labial chaetotaxy ( M 1, M 2, E, L 1 and L 2 setae feathered and r reduced) and the same overall morphology of the foot complex, including the shape of the unguiculi (acuminated) and the number of inner teeth on the ungues (one pair of teeth at the middle and two unpaired at the apex). The femora of the first pair of legs of the males in S. bicolorcornuta  sp. nov. are slightly broadened and the spine-like setae are concentrated in one place ( Fig. 3 EView FIGURE 3). This condition is reminiscent of S. raptora  ( Fig. 1 AView FIGURE 1), excluding the shape of the spines (more elongated in S. bicolorcornuta  sp. nov.) and in their number (14 spines in S. raptora  and eight in S. bicolorcornuta  sp. nov.). The first tibiotarsi of males of S. bicolorcornuta  sp. nov. bear nine spine-like setae ( Fig. 3 FView FIGURE 3) with the same shape and disposal of the eight spines observed on the tibiotarsi of S. raptora  ( Fig. 1 BView FIGURE 1). These two species differ clearly in the chaetotaxy of the cephalic regions 5 and 6, regions 1A and 2 of mesothorax, regions A and B of the second abdominal segments ( Fig. 4View FIGURE 4) and in the number of subapical setae on the venter of manubrium (7+ 7 in S. bicolorcornuta  sp. nov. and 4+ 4 in S. raptora  ). Other characters are compared in Table 2.

Etymology. The species was named after the colour pattern of its antennae.

Distribution. Good’s biogeographic zone 27 ( Good 1974).

Habitat. Seira bicolorcornuta  sp. nov. was found in Alto do Moura municipality, at the State of Pernambuco, northeastern Brazil according to Koeppen’s system ( Kottek et al. 2006). The main climate of the area is ‘As’, that is equatorial and the precipitation conforms to “summer dry conditions ( Kottek et al. 2006). Alto do Moura is located in a transition area between a semi-arid biome called Caatinga and a high marsh-like biome named Brejo de Altitude.

The specimens were collected with an entomological aspirator directly from the ground, near moist sand and granite rocks adjacent to Aluízio Azevedo dam, at the beginning of the dry season.

Discussion

The localities at which S. raptora  and S. bicolorcornuta  sp. nov. were found are close being only 182 km apart. Both municipalities belong to the climate ‘As’ following Koeppen’s system and they are situated in a transitional areas between Caatinga and Brejo de Altitude biomes ( Zeppelini & Bellini 2006). The habitats of Cacimba de Dentro and Alto do Moura where the S. raptora  and S. bicolorcornuta  sp. nov. were found, share, along with the climate, the presence of species of cactus and bromeliads as the predominant flora and acid arenous soil (pH near to 5,0) with the presence of many granitic rocks. The preferred habitat of both species suggests that there is a relation between sexually dimorphic forms and habitat, or alternatively, an ancestral habitat preference. If the later is true, this can give some clue about the paleoenvironments where the species evolved. Neither of these species were found far from the type locality. It is possible that other species with a similar morphological trait occur in other areas, because the fauna of Collembola  of Pernambuco and Paraíba is still poorly known.

There is no doubt that S. bicolorcornuta  sp. nov. and S. raptora  are closely related. They share many morphological similarities and they were found in close proximity to each other. However we believe it is not prudent to create a subgenus for three reasons. First, S. andensis  and S. mirianae  have many similarities with S. bicolorcornuta  sp. nov. and S. raptora  , specially in the head and thoracic chaetotaxy ( Christiansen & Bellinger 2000). They also have a unique condition in New World’s Seira  , which is the lack of macrochaetae on the first abdominal segment. There are no indications of sexual dimorphism in S. andensis  and S. mirianae  , but a re-examination of the legs of males of both species is critical to a clear comprehension of the relationship among the four species. Secondly, other South-American species of Seira  such as S. chimu Jacquemart  and S. cryptica Mari Mutt  have, in some respects, similar patterns of dorsal chaetotaxy as S. bicolorcornuta  sp. nov. and S. raptora  , especially in the head chaetotaxy ( Mari Mutt 1986, Christiansen & Bellinger 2000). However S. chimu  and S. cryptica  have two macrochaetae at the first abdominal segment. We observed the presence of two macrochaetae on the Abd. I in the first four instars of S. raptora  , and at the fifth instar, these macrochaetae became microsetae. Finally, it is not taxonomically useful to create a subgenus with two species if the relationships among the other 177 species of the genus are not analysed. Before dividing Seira  into subgenera it is fundamental to make a phylogenetic analysis of the entire group.

With 21 described species in Brazil, Seira  is now the genus with the higher documented diversity in the country, ( Culik & Zeppelini 2003; Bellini & Zeppelini 2005, 2008). Additional studies are likely to discover more new species.

TABLE 2. Comparison of characters of Seira spp AC = acuminate; A- = minor apical; M+ = larger medial; + = present; - = absent;? = not clearly observed. * Measurements made on Holotype.

Species Lobes on antennal apical bulb Annulations on 4th antennal segment Ratio antenna / cephalic diagonal Unguiculus shape
bicolorcornuta  * 1 - 2.143 AC
raptora  1 - 1.923 AC
mirianae  1-2 - 1.5-2.2 AC
andensis  ? - 1.65 AC

continued.

MNRJ

Brazil, Rio de Janeiro, Sao Cristovao, Universidade do Rio Janeiro, Museu Nacional