Research Article
Print
Research Article
Two new Brazilian species of Loxosceles Heinecken & Lowe, 1832 with remarks on amazonica and rufescens groups (Araneae, Sicariidae)
expand article infoCaroline Sayuri Fukushima‡, Rute Maria Gonçalves de Andrade§, Rogério Bertani‡
‡ Laboratório Especial de Ecologia e Evolução, Instituto Butantan, São Paulo, Brazil
§ Fundação Museu do Homem Americano, São Raimundo Nonato, Brazil

Corresponding author: Caroline Sayuri Fukushima ( carolinesayuri@gmail.com )

Academic editor: Cor Vink
© 2017 Caroline Sayuri Fukushima, Rute Maria Gonçalves de Andrade, Rogério Bertani.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Fukushima CS, Andrade RMG, Bertani R (2017) Two new Brazilian species of Loxosceles Heinecken & Lowe, 1832 with remarks on amazonica and rufescens groups (Araneae, Sicariidae). ZooKeys 667: 67-94. https://doi.org/10.3897/zookeys.667.11369
ZooBank: urn:lsid:zoobank.org:pub:569BC83B-D81E-428E-8AD9-D5A664EC5F49
Open Access

Abstract

The genus Loxosceles Heinecken & Lowe, 1832 has 91 representatives in the New World. Despite medical relevancy, the taxonomy of the genus is poorly understood. South American Loxosceles were divided into four groups of species: laeta, spadicea, gaucho and amazonica; this last one has a single species, Loxosceles amazonica Gertsch, 1967. More recently, the natural occurrence of L. amazonica in the New World has been questioned, due to the strong morphological resemblance and close phylogenetic relationship with Old World species, mainly with Loxosceles rufescens (Dufour, 1820). Herein, L. amazonica is rediagnosed and its morphological variation and natural distribution discussed. Two new species closely related to it from northeastern Brazil are also described, Loxosceles willianilsoni sp. n., from the state of Rio Grande do Norte, and Loxosceles muriciensis sp. n., from the state of Alagoas. The relationships of these new species with L. amazonica and L. rufescens are discussed.

Keywords

Alagoas , Brown recluse spider, Caatinga, Cave, Rio Grande do Norte

Introduction

Loxosceles Heinecken & Lowe, 1832 is a speciose spider genus with a core distribution in the New World (World Spider Catalog 2016). Several species are known also from Africa, Middle East, Mediterranean Europe and two species from China were recently described (World Spider Catalog 2016). Many species were reported as causing bites of importance to human health and several studies on their venom have been published (Gertsch 1967, Tambourgi et al. 2000, Isbister and Fan 2011). Despite this, the taxonomy of the genus is poorly understood. The most comprehensive works were done by Gertsch (1958, 1967) and Gertsch and Ennik (1983) who revised New World species. After these revisions, other species were sporadically described and more recently the African, Middle East and Asian species received more attention (Binford et al. 2008, Duncan et al. 2010, Lotz 2012, Planas and Ribera 2015, Wang 1994).

The South American Loxosceles were revised by Gertsch (1967), who created four groups of species: laeta with 26 species, spadicea with three species, gaucho with six species and amazonica with a single species. Loxosceles amazonica Gertsch, 1967 has been recorded from localities in the Amazon in Brazil, and Peru to northeastern Brazil. More recently, the natural distribution in the New World has been questioned, due to the strong morphological resemblance to the Old World species, mainly with Loxosceles rufescens (Dufour, 1820) (Binford et al. 2008; Duncan et al. 2010). Molecular analyses has also retrieved L. amazonica to be closely related to the Old World species (Binford et al. 2008; Duncan et al. 2010), therefore, L. amazonica origin and its relationship is still up for debate.

Herein, we describe two new species closely related to L. amazonica from northeastern Brazil. The relationship of these new species with L. amazonica and L. rufescens is discussed.

Materials and methods

The general format of the description follows Gertsch (1967). All measurements are in millimeters. Measurements of the legs and palp were taken from the dorsal aspect of the left side (unless appendages were lost or obviously regenerated) with a Mitutoyo® digital caliper, which had an error of 0.005 mm, rounded up to two significant decimals. Structures from the left side of the specimens were chosen for descriptions. When using structures from the right side, the figures were mirrored to show them as coming from the left side and allowing easy comparison. The copulatory organs of females were dissected and submitted to digestion by a commercial protein remover for contact lenses (with pancreatin) during some minutes in order to observe the internal structure; when necessary, they were also cleared with clove oil. A Leica LAS Montage and LAS 3D module mounted on a Leica M205C dissecting microscope were used for image capture and measurements of other spider structures.

Abbreviations

ALE anterior lateral eye,

ESEC Ecological Station,

FLONA National Forest,

PARNA National Park,

PLE posterior lateral eye,

PME posterior median eye.

The examined specimens are deposited at MNRJ, Museu Nacional, Rio de Janeiro, and AMNH, American Museum of Natural History, New York. Geographical coordinates are denoted as primary sources between round brackets, secondary sources (Google Earth) between square brackets. The coordinates from the secondary source were obtained from the center of the municipality cited in the specimen label and are in DMS (Degrees, Minutes and Seconds) format rounded off to minutes. Maps were made with SimpleMappr, an online tool used to produce maps (Shorthouse 2010).

Taxonomy

Loxosceles amazonica Gertsch, 1967

Figs 1–6, 7–13, 14–17, 18–21, 22–25, 26–31, 32–35, 36–39, 40–47, 48–51, 78–79

Loxosceles amazonica Gertsch, 1967: 143, pl. 4, figs 7−10, pl. 5, figs 6−7 (female holotype examined (AMNH), Brazil, state of Mato Grosso, Santa Isabel, Araguaia river, Mato Grosso side, 15–25 July 1957, B. Malkin col., receptacles not in the vial); Lucas, Cardoso and Moraes 1986: 130, figs 3−4; Duncan et al. 2010: 241, fig. 3; World Spider Catalog 2016.

Material examined

(Table 3). BRAZIL: Piauí, Serra Branca, Parque Nacional Serra da Capivara, São Raimundo Nonato [9°00'S, 42°41'W], 1 male, 1 female and 11 immatures, R. M. Gonçalves Andrade col. (MNRJ 6927); Rio Grande do Norte: Serra Negra do Norte, ESEC Seridó (6°34'S, 37°15'W), 2 females and 5 males, C. S. Fukushima, K. C. T. Riciluca and N. M. Gonçalves col., 14 March 2014, ref. Ser 8, 12, 2, 7, 9, 10, 33, respectively (MNRJ 6928); 1 female, under tree bark, during the night, C. S. Fukushima col., 14 March 2014, ref. C28 (MNRJ 6929); 1 female, C. S. Fukushima col., 14 March 2014, inside tree trunk, during the day, ref. C44 (MNRJ 6930); 1 male, C. S. Fukushima col., 14 March 2014, ref. C41 (MNRJ 7303); Açu, FLONA de Açu (5°34'S, 36°56'W), 1 female, under old house debris, during the night, L. Monteiro col., 30 October 2014, ref. L72 (MNRJ 6931); 1 female, under tree bark, during the day, C. S. Fukushima col., 30 October 2014, ref. C599 (MNRJ 6932); 1 female, near Carnaúba trees, during the day, K. C. T. Riciluca col., 26 March 2014, ref. K137 (MNRJ 6933); 1 female, in a vacated old house during the night, C. S. Fukushima col., 23 March 2014, ref. C163 (MNRJ 6934); 1 male, under roof tiles, C. S. Fukushima col., 23 March 2014, ref. C167g (MNRJ 6935); 1 male, under roof tiles, C. S. Fukushima col., 23 March 2014, ref. C167o (MNRJ 6936); 1 male, under roof tiles, C. S. Fukushima col., 30 October 2014, ref. C631 (MNRJ 6937); 1 male, in fallen Carnaúba tree, during the night, N. M. Gonçalves col., 25 March 2014, ref. N186 (MNRJ 6938); 1 male, under roof tiles, during the night, C. S. Fukushima col., 23 March 2014, ref. XXXI (MNRJ 6939); 1 female, K. C. T. Riciluca col., March 2014, ref. K133 (MNRJ 7305); Martins (6°04'S, 37°54'W), 1 female, Mirante-Casa de Pedra cave track, during the night, C. S. Fukushima col., 20 March 2014, ref. C144 (MNRJ 6940); 1 female, near Casa de Pedra cave, during the day, N. M. Gonçalves col., 19 March 2014, ref. N81 (MNRJ 6941); 1 female, Mirante-Casa de Pedra cave track, during the day, N. M. Gonçalves col., 20 March 2014, ref. N91 (MNRJ 6942); 1 female, under fallen tree, near grange of Sr. Clesinho, during the day, A. P. L. Giupponi col., 23 October 2014, ref. A132 (MNRJ 6943), 1 female, near Casa de Pedra cave, under rock, during the night, C. S. Fukushima col., 23 October 2014, ref. C495 (MNRJ 6944); 1 male, in a ravine near Casa de Pedra cave, during the night, K. C. T. Riciluca col., 19 March 2014, ref. K59 (MNRJ 6945); 1 male, near Casa de Pedra cave, during the day, C. S. Fukushima col., 19 March 2014, ref. C103 (MNRJ 6946); 1 male, in a ravine, C. S. Fukushima col., 19 March 2014, ref. C116 (MNRJ 6947); 1 female, near Casa de Pedra cave, C. S. Fukushima col., 23 October 2014, ref. C497; 1 male, Mirante-Casa de Pedra cave track, C. S. Fukushima col., 20 March 2014, ref. C148 (MNRJ 7306); Macaíba, Escola Agrícola de Jundiaí (5°53'S, 35°21'W), 1 male (MNRJ 6948) and 1 female (MNRJ 6949), in a tree trunk during the night, C. S. Fukushima and W. Pessoa col., 13 September 2013 (ref. AV046, AV047, respectively); Ceará, Santa Quitéria (4°19'S, 40°09'W), 1 male and 1 immature male, D. R. Pedroso col., 3–12 February 2014 (MNRJ 6950); 1 male, 1 female and 9 immatures, Gruta W13, SAD’69, Camp 1, F. Pellegatti & D. R. Pedroso col., 3–13 February 2014 (MNRJ 6952).

Diagnosis

Males of L. amazonica resemble those of Loxosceles rufescens, Loxosceles bentejui Planas & Ribera, 2015, Loxosceles foutadjalloni Millot, 1941, Loxosceles guayota Planas & Ribera, 2015, Loxosceles hupalupa Planas & Ribera, 2015, Loxosceles lacta Wang, 1994, Loxosceles mahan Planas & Ribera, 2015, Loxosceles tazarte Planas & Ribera, 2015, Loxosceles tibicena Planas & Ribera, 2015, Loxosceles willianilsoni sp. n., and Loxosceles muriciensis sp. n. by incrassated palpal tibia, longer than cymbium (Figs 1–2). They differ from those of L. hupalupa, L. mahan and L. tazarte by having shorter embolus (Figs 1–2), and entire pars cephalica as well as carapace border dark brown (Fig. 14), best seen in live specimens. From those of L. rufescens, L. bentejui, L. foutadjalloni, L. guayota, L. lacta, L. tibicena, L. willianilsoni sp. n. and L. muriciensis sp. n., they can be distinguished by having embolus with a mild retrolateral curvature along its length (Fig. 11). Females of L. amazonica resemble those of L. rufescens, L. bentejui, L. foutadjalloni, L. hupalupa, L. lacta, L. mahan, L. tazarte, L. tibicena, L. willianilsoni sp. n. and L. muriciensis sp. n. by having spermathecae with large seminal receptacles and dark sclerotized lateral bands (Fig. 26). Females of L. amazonica can be distinguished from all these species by a cluster of globular lobes on apex of seminal receptacles (Figs 26–31). Additionally, L. amazonica males and females can be distinguished from L. mahan, L. tazarte, L. bentejui, L. guayota, L. tibicena and L. hupalupa by lacking a conspicuous dark V-mark posteriorly on pars cephalica.

Natural history

Despite its specific epithet, L. amazonica specimens were found in areas covered by caatinga (Figs 36–47), a semi-arid vegetation found in northeastern Brazil (Fig. 78). At FLONA de Açu, specimens were found under rocks and tree bark, and also under or inside fallen trees, especially carnaúbas (Copernicia prunifera Miller) (Figs 36–39). They were also found at vacant old houses inside an area of conservation unit, and under house debris near the FLONA’s base.

The ESEC Seridó is located on a sui generis region of the state of Rio Grande do Norte characterized by a hyper-xerophilous, arboreal-shrubby caatinga, with irregular precipitation of 500 to 800 mm/year (Varella-Freire 2002). Specimens of L. amazonica were found throughout different landscapes of the ESEC (Figs 40–43). They were found under rocks and tree bark in shaded areas (Fig. 44), inside termite nests (Fig. 47) or cracks of rocky outcrops (Fig. 45), under fallen trees (Fig. 46) or under house debris near ESEC’s base.

Specimens of L. amazonica were also found in Martins, state of Rio Grande do Norte, “a brejo de altitude” region, i.e. an area covered by humid forest surrounded by arid caatinga (Pereira Filho and Montingelli 2011), usually over mountains and hillsides with an elevation of more than 500 m (Ruiz-Esparza 2009) and that receives more than 1,200 mm of orographic rains (Prado 2003, in Ruiz-Esparza 2009). We found specimens of L. amazonica in ravines near the town (Fig. 48), in a trail on the top on the hill (Fig. 49) and under old house debris close to more humid and higher areas (about 700 m a.s.l.) (Fig. 50), as well as under rocks and tree bark near Casa de Pedra cave, in a lower region with caatinga vegetation (about 300 m a.s.l.) (Fig. 51). No specimens were found inside Casa de Pedra cave.

Spermatheca variation

(see Fig. 79). Specimens vary in number and size of globular lobes on spermatheca apex and seminal receptacles proportions. Specimens from Martins and Macaíba in the State of Rio Grande do Norte (Figs 26 and 31, respectively), São Raimundo Nonato, state of Piauí (Fig. 27) and Santa Quitéria, state of Ceará (Fig. 30) have three to six lobes in each spermatheca, more or less similar in size. The seminal receptacles of specimens of these areas are slightly short and trapezoid. On the other hand, specimens of ESEC Seridó and FLONA de Açu, both in the state of Rio Grande do Norte (Figs 28 and 29, respectively) have four to five lobes, usually one of them larger than the others. The seminal receptacles are slightly longer, with a triangular shape.

It is not clear how these genitalic traits vary along the distribution of L. amazonica or if these variations reflect a higher diversity in amazonica lineage. Variation in the morphology of palps and spermatheca of other Loxosceles species has already been noted, such as in L. rufescens (Brignoli 1969). However, Duncan et al. (2010) recovered a monophyletic group of specimens that morphologically resemble L. rufescens, within which there are divergent clusters of specimens and populations, but with genetic distances high enough to be considered as cryptic species. In the same way, the slight morphological variations in L. amazonica could correspond to separated species, only detectable through a molecular approach, which was beyond the scope of this study.

Figures 1–6. 

Loxosceles amazonica, male palpal bulbs. 1–2 Serra Negra do Norte, ESEC Seridó, state of Rio Grande do Norte, Brazil (MNRJ 6928, ref. Ser 7), left palp. 1 retrolateral 2 prolateral 3–4 Açu, FLONA de Açu, state of Rio Grande do Norte, Brazil (MNRJ 6939), left palp 3 retrolateral 4 prolateral 5–6 Martins, state of Rio Grande do Norte, Brazil (MNRJ 7306), right palp (mirrored) 5 retrolateral 6 prolateral. Scale bars: 1mm.

Figures 7–13. 

Loxosceles amazonica, male palpal bulbs, left palp. 7–8 Santa Quitéria, state of Ceará, Brazil (MNRJ 6950) 7 retrolateral 8 prolateral 9–10 São Raimundo Nonato, state of Piauí, Brazil (MNRJ 6927, ref. GSB11A-17) 9 retrolateral 10 prolateral. 11–13 dorsal 11 Açu, FLONA de Açu, state of Rio Grande do Norte, Brazil (MNRJ 6936) 12 Serra Negra do Norte, ESEC Seridó, state of Rio Grande do Norte, Brazil (MNRJ 6928, ref. Ser 7) 13 Santa Quitéria, state of Ceará, Brazil (MNRJ 6950). Scale bars: 1mm.

Figures 14–17. 

Loxosceles amazonica, male carapace. 14–15 Açu, FLONA de Açu, state of Rio Grande do Norte, Brazil 14MNRJ 6935 15MNRJ 6936 16 Serra Negra do Norte, ESEC Seridó, state of Rio Grande do Norte, Brazil (MNRJ 6928, ref. Ser 7) 17 Martins, state of Rio Grande do Norte, Brazil (MNRJ 6947). Scale bars: 1mm.

Figures 18–21. 

Loxosceles amazonica, carapace. 18–19 Male 18 São Raimundo Nonato, state of Piauí, Brazil (MNRJ 6927, ref. GSB11A-17) 19 Santa Quitéria, state of Ceará, Brazil (MNRJ 6950) 20–21 Female 20 holotype, Santa Isabel, state of Mato Grosso, Brazil (AMNH) 21 Açu, FLONA de Açu, state of Rio Grande do Norte, Brazil (MNRJ 7305). Scale bars: 1mm.

Figures 22–25. 

Loxosceles amazonica, carapace, female. 22 Martins, state of Rio Grande do Norte, Brazil (MNRJ 7304) 23 Serra Negra do Norte, ESEC Seridó, state of Rio Grande do Norte, Brazil (MNRJ 6928, ref. Ser 8) 24 Santa Quitéria, state of Ceará, Brazil (MNRJ 6952) 25 São Raimundo Nonato, state of Piauí, Brazil (MNRJ 6927, ref. GSB11A-17). Scale bars: 1mm.

Figures 26–31. 

Loxosceles amazonica, seminal receptacles. 26 Martins, state of Rio Grande do Norte, Brazil (MNRJ 6942) 27 São Raimundo Nonato, state of Piauí, Brazil (MNRJ 6927, ref. GSB11A-17) 28 Serra Negra do Norte, ESEC Seridó, state of Rio Grande do Norte, Brazil (MNRJ 6928, ref. Ser 8) 29 Açu, FLONA de Açu, state of Rio Grande do Norte, Brazil (MNRJ 6931) 30 Santa Quitéria, state of Ceará, Brazil (MNRJ 6952) 31 Macaíba, state of Rio Grande do Norte, Brazil (MNRJ 6949). Scale bars: 27–29 1 mm; 26, 30–31 0.5 mm.

Figures 32–35. 

Loxosceles amazonica, habitus. 32–34 Female 32 Martins, state of Rio Grande do Norte, Brazil 33 Açu, FLONA de Açu, state of Rio Grande do Norte, Brazil 34 Macaíba, state of Rio Grande do Norte, Brazil 35 Male. Açu, FLONA de Açu, state of Rio Grande do Norte, Brazil (MNRJ 6936). Photos C. S. Fukushima.

Figures 36–39. 

Loxosceles amazonica habitats in FLONA de Açu, Açu, state of Rio Grande do Norte, Brazil 36 Carnaúba trees 37 fallen Carnaúba tree, in detail web of L. amazonica 38 caatinga vegetation in rainy season 39 caatinga vegetation in dry season. Photos C. S. Fukushima.

Figures 40–47. 

Loxosceles amazonica habitats in ESEC Seridó, Serra Negra do Norte, state of Rio Grande do Norte, Brazil. 40 large rocky outcrops 41 hyper-xerophilous, arboreal-shrubby caatinga in rainy season 42 dry temporary lagoon 43 grass areas over neosoil 44 fallen dead tree trunk in shaded area 45 small rocky outcrops 46 web of L. amazonica inside rotten tree trunk 47 web of L. amazonica inside termite nest. Photos C. S. Fukushima.

Figures 48–51. 

Loxosceles amazonica habitats in Martins, state of Rio Grande do Norte, Brazil 48 ravine in a humid area near town 49 under rocks at Mirante-Casa de Pedra cave trail 50 under debris of old house in rural area 51 in caatinga vegetation close to Casa de Pedra cave. Photos C. S. Fukushima.

Loxosceles willianilsoni sp. n.

http://zoobank.org/DE5FF5FD-1637-461A-ACBD-93A670CC6E1F
Figs 52–55, 56–57, 58–61, 62–65, 66–69, 78–79

Material examined

(Table 3). Male holotype (MNRJ 6953) and female paratype (MNRJ 6954), BRAZIL: Rio Grande do Norte, Martins, Casa de Pedra cave (06°05'S, 37°55'W), C. S. Fukushima col., 2014.

Other material examined

(Table 3). Casa de Pedra cave (06°05'S, 37°55'W), 319 m a.s.l., 1 female, A. P. L. Giupponi col., 2014, ref. A100 (MNRJ 6955); 1 female, N. M. Gonçalves col., 2014, ref. N60 (MNRJ 6956); 1 female, N. M. Gonçalves col., 2014, ref. N63 (MNRJ 6957); 1 female, C. S. Fukushima col., 2014, ref. C92 (MNRJ 6958); 1 female, C. S. Fukushima col., 2014, ref. C481 (MNRJ 6959); 1 male, N. M. Gonçalves col., 2014, ref. N59 (MNRJ 6960); 1 male, A. P. L Giupponi col., 2014, ref. A107 (MNRJ 6961); 1 male, C. S. Fukushima col., ref. C76 (MNRJ 6962); 1 male, K. C. T. Riciluca col., 2014, ref. K33 (MNRJ 6963); 1 male, A. P. L. Giupponi col., 2014, ref. A102 (MNRJ 6964); 1 male, C. S. Fukushima col., 2014, ref. C64 (MNRJ 6965); 1 male, C. S. Fukushima col., 2014, ref. C72 (MNRJ 6966), 1 female, C. S. Fukushima col, 2014, ref. C479 (MNRJ 6951).

Diagnosis

Males of Loxosceles willianilsoni sp. n. resemble those of L. amazonica, L. rufescens, L. bentejui, L. foutadjalloni, L. guayota, L. hupalupa, L. lacta, L. mahan, L. tazarte, L. tibicena, and L. muriciensis sp. n. by incrassated palpal tibia, longer than cymbium (Fig. 54). They differ from those of L. hupalupa, L. mahan and L. tazarte by having shorter embolus (Fig. 54), and entire pars cephalica as well as carapace border dark brown (Fig. 52), best seen in live specimens. From those of L. amazonica, L. rufescens, L. bentejui, L. foutadjalloni, L. guayota, L. lacta, L. tibicena, and L. muriciensis sp. n. they can be distinguished by having straight embolus with a strong curvature on its apex (Fig. 53). Additionally, males of L. willianilsoni sp. n. differ from those of all these species except L. foutadjalloni, L. guayota, and L. muriciensis sp. n. by having leg I at least eight times as long as carapace (Table 1). Females of L. willianilsoni sp. n. resemble females of L. amazonica, L. rufescens, L. bentejui, L. foutadjalloni, L. hupalupa, L. lacta, L. mahan, L. tazarte, L. tibicena, and L. muriciensis sp. n. by having spermathecae with large seminal receptacles and dark sclerotized lateral bands (Fig. 57). Females of L. willianilsoni sp. n. can be distinguished from all these species by the combination of the following characters: spermathecae with dark sclerotized lateral bands almost reaching their apex, which has no lobes and no constriction forming a neck (Figs 57–61), leg I at least 6.5 times as long as carapace (Table 2). Additionally, L. willianilsoni sp. n. males and females can be distinguished from L. mahan, L. tazarte, L. bentejui, L. guayota, L. tibicena and L. hupalupa by lacking a conspicuous dark V-mark posteriorly on pars cephalica.

Description

Male holotype (MNRJ 6953). Total length 7.39. Carapace 3.16 long, 2.74 wide. Eye sizes and interdistances: ALE 0.15, PME 0.21, PLE 0.18, PME-PLE 0.02, PME-ALE 0.15; clypeus 0.26. Leg formula II, I, IV, III. Legs length: leg I: femur 7.47, patella 0.98, tibia 8.37, metatarsus 8.85, tarsus 1.77, total 27.44; II: 8.29, 1.11, 9.88, 10.95, 1.85, 32.08; III: 6.40, 1.09, 6.23, 7.64, 1.30, 22.66; IV: 7.12, 1.05, 7.08, 8.38, 1.52, 26.15. Palp: femur 1.46 long, 0.31 wide; patella 0.49 long, 0.33 wide; tibia 0.88 long, 0.48 wide; cymbium 0.43 long, 0.42 wide. Labium 0.71 long, 0.38 wide. Sternum 1.78 long, 1.50 wide. Femur I 2.4 times as long, tibia I 2.7 times as long and leg I 8.7 as long as carapace. Palpal femur four times longer than wide, tibia 1.8 times longer than wide, cymbium oval (Fig. 54). Bulb suboval and approximately same size as cymbium. Embolus straight, with a strong curvature on apex, approximately 1.3 times longer than bulb length in retrolateral view, without carina (Fig. 53). Cephalic region of carapace covered by many long setae (Fig. 52). Entire pars cephalica as well as carapace border dark brown (Fig. 52). Legs and palps light brown, covered by short greyish setae on the femora and patellae (Fig. 64). Endites, coxae and sternum light brown. Labium dark brown.

Female paratype (MNRJ 6954): As in male, except: Total length 8.72. Carapace 2.99 long, 2.39 wide. Eye sizes and interdistances: ALE 0.14, PME 0.17, PLE 0.16, PME-PLE 0.02, PME-ALE 0.19; clypeus 0.35. Leg formula II, I, IV, III. Legs length: leg I: femur 5.25, patella 1.17, tibia 5.93, metatarsus 5.88, tarsus 1.24, total 19.47; II: 5.96, 1.14, 6.40, 6.32, 1.50, 21.32; III: 4.76, 1.00, 4.22, 4.80, 1.19, 15.97; IV: 5.32, 1.15, 4.89, 5.96, 1.40, 18.72. Palp: femur 0.98 long, 0.21 wide; patella 0.28 long, 0.25 wide; tibia 0.70 long, 0.20 wide; tarsus 1.06 long, 0.16 wide. Labium 0.53 long, 0.44 wide. Sternum 1.63 long, 1.38 wide. Femur I 1.8 times as long, tibia I 2.0 times as long and leg I 6.5 as long as carapace. Palpal femur 4.7 times longer than wide, tibia 3.5 longer than wide, tarsus not incrassate. Spermathecae with enlarged seminal receptacles; without transversal plate; and presence of dark sclerotized lateral bands almost reaching the apex (Fig. 57). Palps pale brown, except by darker tibiae and metatarsi. Endites pale brown.

Etymology

This species is named after the biology student Willianilson Pessoa, in honor of his friendship and support during expeditions in Rio Grande do Norte. This name is masculine in gender.

Natural history

Specimens were found inside Casa de Pedra cave walking on walls, in webs inside wall cracks or under loose stones on the cave ground. This calcarian cave is very large regarding regional patterns and has turistic use (Ferreira et al. 2010). Apparently, specimens of L. willianilsoni sp. n. are found only inside the cave.

Figures 52–55. 

Loxosceles willianilsoni sp. n., male holotype (MNRJ 6953). 52 carapace 53–55 left palpal bulb 53 dorsal 54 prolateral 55 retrolateral. Scale bar 1mm.

Figures 56–57. 

Loxosceles willianilsoni sp. n., female paratype (MNRJ 6954). 56 carapace 57 seminal receptacles. Scale bar: 1 mm.

Figures 58–61. 

Loxosceles willianilsoni sp. n., seminal receptacles variation. 58MNRJ 6957 59MNRJ 6956 60MNRJ 6959 61MNRJ 6951. Scale bars: 58–60 1 mm; 61 0.5 mm.

Figures 62–65. 

Loxosceles willianilsoni sp. n., habitus. 62 specimen walking inside Casa de Pedra cave 63 female 64 male 65 carapace pattern, male. Photos 62, 64 C. S. Fukushima; 63, 65 R. Bertani.

Figures 66–69. 

Loxosceles willianilsoni sp. n. habitat in Martins, state of Rio Grande do Norte, Brazil 66 Casa de Pedra cave 67 entrance of the cave 68–69 caatinga vegetation surrounding the cave 68 dry season 69 rainy season. Photos C. S. Fukushima.

Loxosceles muriciensis sp. n.

http://zoobank.org/CC85E3A6-44F7-4C7C-BCBD-EA9002A7309F
Figs 70–73, 74–75, 76–77, 78–79

Material examined

(Table 3). Male holotype (MNRJ 6967) and female and male paratypes (MNRJ 6968), BRAZIL: Alagoas, Murici, Estação Ecológica de Murici (9°15'S, 35°48'W), 23.1°C, 84% URA, under the bark of a large burnt tree, R. Bertani, D. R. M. Ortega and R. H. Nagahama col., 13 August 2006.

Diagnosis

Males of L. muriciensis sp. n. resemble those of L. amazonica, L. rufescens, L. bentejui, L. foutadjalloni, L. guayota, L. hupalupa, L. lacta, L. mahan, L. tazarte, L. tibicena and L. willianilsoni sp. n. by incrassated palpal tibia, longer than cymbium (Fig. 72). Males differ from those of L. hupalupa, L. mahan and L. tazarte by having shorter embolus (Fig. 72), and entire pars cephalica as well as carapace border dark brown (Fig. 70), best seen in live specimens. Males of L. muriciensis sp. n. differ from those of L. amazonica, L. rufescens, L. bentejui, L. foutadjalloni, L. guayota, L. lacta, L. tibicena, and L. willianilsoni sp. n. by having straight embolus with a mild curvature on apex, forming a hook (Fig. 71). Additionally, males of Loxosceles muriciensis sp. n. differ from males of all these species except L. foutadjalloni, L. guayota and L. willianilsoni sp. n. by having leg I at least eight times as long as carapace (Table 1). Females of L. muriciensis sp. n. resemble those of L. amazonica, L. rufescens, L. bentejui, L. foutadjalloni, L. hupalupa, L. lacta, L. mahan, L. tazarte, L. tibicena, and L. willianilsoni sp. n. by having spermathecae with large seminal receptacles and dark sclerotized lateral bands (Fig. 75). Females of L. muriciensis sp. n. can be distinguished from all these species by the following combination of characters: spermathecae with dark sclerotized lateral bands almost reaching their apex, which has two well-developed lobes, and no constriction forming a neck (Fig. 75); leg I more than five times as long as carapace (Table 2). Additionally, L. muriciensis sp. n. males and females can be distinguished from L. mahan, L. tazarte, L. bentejui, L. guayota, L. tibicena and L. hupalupa by lacking a conspicuous dark V-mark posteriorly on pars cephalica.

Description

Male holotype (MNRJ 6967). Total length 5.46. Carapace 2.21 long, 2.10 wide. Eye sizes and interdistances: ALE 0.12, PME 0.16, PLE 0.16, PME-PLE 0.02, PME-ALE 0.12; clypeus 0.30. Leg formula II, I, IV, III. Legs length: leg I: femur 4.73, patella 0.90, tibia 5.20, metatarsus 5.65, tarsus 1.42, total 17.9; II: 5.15, 0.95, 5.13, 6.39, 1.45, 19.07; III: 4.21. 0.70. 3.73. 4.37. 0.93. 13.94; IV: 4.77. 0.69. 4.55. 5.55. 1.15. 16.71. Palp: femur 1.12 long, 0.30 wide; patella 0.46 long, 0.35 wide; tibia 0.70 long, 0.55 wide; cymbium 0.50 long, 0.35 wide. Labium 0.49 long, 0.33 wide. Sternum 1.23 long, 1.16 wide. Femur I 2.2 times as long, tibia I 2.4 times as long and leg I 8.1 as long as carapace. Palpal femur 3.7 times longer than wide, tibia 1.3 times longer than wide, cymbium oval (Fig. 72). Bulb suboval and larger than cymbium. Embolus straight, with a mild curvature on apex, approximately 1.6 times longer than bulb length in retrolateral view, without carina (Fig. 71). Cephalic region of carapace covered by many long setae (Fig. 70). Entire pars cephalica as well as carapace border dark brown (Fig. 70). Legs and palps light brown, covered by short greyish setae on the femora and patellae. Endites, coxae and sternum light brown. Labium dark brown.

Female paratype (MNRJ 6968): As in male, except: Total length 8.65. Carapace 2.98 long, 2.80 wide. Eye sizes and interdistances: ALE 0.15, PME 0.21, PLE 0.20, PME-PLE 0.05, PME-ALE 0.17; clypeus 0.40. Leg formula II, I, IV, III. Legs length: leg I: femur 4.51, patella 1.13, tibia 4.50, metatarsus 4.35, tarsus 1.45, total 15.94; II: 5.05, 1.06, 5.33, 3.41, 1.30, 16.15; III: 4.25, 1.05, 3.55, 4.30, 1.02, 14.17; IV: 4.55, 0.62, 4.50, 3.45, 1.22, 14.34. Palp: femur 1.20 long, 0.25 wide; patella 0.37 long, 0.31 wide; tibia 0.71 long, 0.25 wide; tarsus 1.07 long, 0.17 wide. Labium 0.58 long, 0.50 wide. Sternum 1.84 long, 1.40 wide. Femur I 1.5 times as long, tibia I 1.5 times as long and leg I 5.3 as long as carapace. Palpal femur 4.8 times longer than wide, tibia 2.8 longer than wide, tarsus not incrassate. Spermathecae with enlarged seminal receptacles; without transversal plate, lacking a constriction near apex forming a neck; presence of two well-developed lobes on apex and dark sclerotized lateral bands almost reaching apex (Fig. 75). Palps brown, except by pale patellae and femora. Endites pale brown.

Etymology

The specific name refers to the type locality, Estação Ecológica de Murici, state of Alagoas, Brazil and is neutral in gender.

Natural history

The few specimens of L muriciensis sp. n. were found inside a burnt tree in an Atlantic rainforest conservation unit in the state of Alagoas. The ESEC Murici is one of the last and largest remnants of the northeastern Atlantic rainforest and it is inserted in a biodiversity hotspot known as the “Pernambuco Endemism Center” (Nemésio and Santos Junior 2014).

Figures 70–73. 

Loxosceles muriciensis sp. n., male holotype. 70 carapace 71–73 right palpal bulb 71 dorsal (mirrored) 72 prolateral (mirrored) 73 retrolateral (mirrored). Scale bars: 70, 72–73 1mm;71 0.5mm.

Figures 74–75. 

Loxosceles muriciensis sp. n., female paratype. 74 carapace 75 seminal receptacles. Scale bars: 1 mm.

Figures 76–77. 

Loxosceles muriciensis sp. n. male holotype, habitus. 76 overall aspect 77 carapace pattern. Photos R. Bertani.

Figures 78–79. 

78 Map showing records of L. amazonica, L. willianilsoni sp. n. and L. muriciensis sp. n. Area inside rectangle represented on Figure 79. Records of L. amazonica include also those from Azevedo et al. (2014), Gertsch (1967) and Silveira (2015). 79 Expanded map showing the records of the illustrated specimens of L. amazonica, L. willianilsoni sp. n. and L. muriciensis sp. n.

Table 1.
Download as
CSV
XLSX

Loxosceles spp. of rufescens group, males. Carapace and leg I measurements. Data from (1) Gertsch (1967), (2) Lotz (2012), (3) Planas and Ribera (2015). Legs differentiated by less than 0.5 mm are in bold. AL = state of Alagoas, AM = state of Amazonas, CE = state of Ceará, PI = state of Piauí, RN = state of Rio Grande do Norte.

Taxon Locality Specimen Carapace Leg I Leg I / Carapace Leg Formula
L. amazonica 1 Gurupá (AM), Brazil paratype 4 19.5 4.88 2, 4, 1, 3
L. amazonica FLONA Açu (RN), Brazil MNRJ 6936 3.87 22.11 5.72 2, 4, 1, 3
L. amazonica ESEC Seridó (RN), Brazil MNRJ 7303 3.26 17.57 5.39 2, 4, 1, 3
L. amazonica Martins (RN), Brazil MNRJ 6947 3.12 16.94 5.43 2, 4, 1, 3
L. amazonica Macaíba (RN), Brazil MNRJ 6948 2.86 15.95 5.58 2, 4, 1, 3
L. amazonica São Raimundo Nonato (PI), Brazil MNRJ 6927 2.62 16.39 6.25 2, 4, 1, 3
L. amazonica Santa Quitéria (CE), Brazil MNRJ 6950 2.76 20.81 7.54 2, 4, 1, 3
L. willianilsoni sp. n. Martins (RN), Brazil holotype 3.16 27.44 8.69 2, 1, 4, 3
L. muriciensis sp. n. Murici (AL), Brazil holotype 2.21 17.9 8.12 2, 1, 4, 3
L. rufescens 1 Rome, Italy AMNH 3 20.1 6.70 2, 4, 1, 3
L. foutadjalloni 2 Guinea lectotype 4 45.9 11.48 2, 1, 4, 3
L. mahan 3 Canary Islands holotype 2.89 17.37 6.01 2, 4, 1, 3
L. tazarte 3 Canary Islands holotype 2.34 15.42 6.59 2, 1, 4, 3
L. bentejui 3 Canary Islands holotype 2.91 20.63 7.09 2, 1, 4, 3
L. tibicena 3 Canary Islands holotype 2.63 20.19 7.68 2, 4, 1, 3
L. guayota 3 Canary Islands holotype 3.62 34.78 9.61 2, 1, 4, 3
L. hupalupa 3 Canary Islands holotype 2.51 19.51 7.77 2, 4, 1, 3
Table 2.
Download as
CSV
XLSX

Loxosceles spp. of rufescens group, females. Carapace and leg I measurements. Data from (1) Gertsch (1967), (2) Lotz (2012), (3) Planas and Ribera (2015). Legs differentiated by less than 0.5 mm are in bold. * = Legs 2 and 4, and legs 4 and 1 have difference in length less than 0.5 mm. AL = state of Alagoas, CE = state of Ceará, MT = state of Mato Grosso, PI = state of Piauí, RN = state of Rio Grande do Norte.

Taxon Locality Specimen Carapace Leg I Leg I / Carapace Leg Formula
L. amazonica Santa Isabel (MT), Brazil holotype 4.17 19.04 4.57 2, 4, 1, 3
L. amazonica Açu (RN), Brazil MNRJ 6933 3.82 17.32 4.53 2, 4, 1, 3
L. amazonica Serra Negra do Norte (RN), Brazil MNRJ 6928 3.89 17.60 4.52 2, 4, 1, 3*
L. amazonica Martins (RN), Brazil MNRJ 6940 3.83 17.63 4.60 2, 4, 1, 3
L. amazonica Macaíba (RN), Brazil MNRJ 6949 3.45 14.06 4.08 Missing legs 3 and 4
L. amazonica São Raimundo Nonato (PI), Brazil MNRJ 6927 3.08 12.48 4.06 2, 4, 1, 3*
L. amazonica Santa Quitéria (CE), Brazil MNRJ 6952 2.86 16.56 5.79 2, 4, 1, 3
L. willianilsoni sp. n. Martins(RN), Brazil paratype 2.99 19.47 6.52 2, 1, 4, 3
L. muriciensis sp. n. Murici (AL), Brazil paratype 2.98 15.94 5.34 2, 1, 4, 3
L. rufescens 1 Alto Douro, Portugal AMNH 3.2 15.4 4.81 2, 4, 1, 3
L. foutadjalloni 2 Guinea paralectotype 3.9 26.8 6.87 2, 1, 4, 3
L. mahan 3 Canary Islands paratype 2.97 12.97 4.37 2, 4, 1, 3
L. tazarte 3 Canary Islands paratype 2.88 14.65 5.09 2, 4, 1, 3
L. bentejui 3 Canary Islands paratype 3.35 16.78 5.01 2, 4, 1, 3
L. tibicena 3 Canary Islands paratype 3.35 18.43 5.50 2, 4, 1, 3
L. hupalupa 3 Canary Islands paratype 3.71 23.09 6.22 Missing leg 4
Table 3.
Download as
CSV
XLSX

Localities of all the material studied. F = female, J = juvenile, M= male, MJ= immature male.

Species Quantity Number Locality Coordinates
L. amazonica 1M, 1F, 11J MNRJ 6927 PARNA Serra da Capivara, São Raimundo Nonato, Piauí, Brazil [9°00'S, 42°41'W]
5M, 2F MNRJ 6928 ESEC Seridó, Serra Negra do Norte, Rio Grande do Norte, Brazil (6°34'S, 37°15'W)
1F MNRJ 6929
1F MNRJ 6930
1M MNRJ 7303
1F MNRJ 6931 FLONA de Açu, Açu, Rio Grande do Norte, Brazil (5°34'S, 36°56'W)
1F MNRJ 6932
1F MNRJ 6933
1F MNRJ 6934
1M MNRJ 6935
1M MNRJ 6936
1M MNRJ 6937
1M MNRJ 6938
1M MNRJ 6939
1F MNRJ 7305
1F MNRJ 6940 Martins, Rio Grande do Norte, Brazil (6°04'S, 37°54'W)
1F MNRJ 6941
1F MNRJ 6942
1F MNRJ 6943
1F MNRJ 6944
1M MNRJ 6945
1M MNRJ 6946
1M MNRJ 6947
1M MNRJ 7306
1F MNRJ 7304
1M MNRJ 6948 Macaíba, Rio Grande do Norte, Brazil (5°53'S, 35°21'W)
1F MNRJ 6949
1M, 1MJ MNRJ 6950 Santa Quitéria, Ceará, Brazil (4°19'S, 40°09'W)
1M, 1F, 9J MNRJ 6952
L. willianilsoni sp. n. 1M MNRJ 6953 Casa de Pedra cave, Martins, Rio Grande do Norte, Brazil (06°05'S, 37°55'W)
1F MNRJ 6954
1F MNRJ 6955
1F MNRJ 6956
1F MNRJ 6957
1F MNRJ 6958
1F MNRJ 6959
1M MNRJ 6960
1M MNRJ 6961
1M MNRJ 6962
1M MNRJ 6963
1M MNRJ 6964
1M MNRJ 6965
1M MNRJ 6966
1F MNRJ 6951
L. muriciensis sp. n. 1M MNRJ 6967 Murici, Alagoas, Brazil (9°15'S, 35°48'W)
1F, 1M MNRJ 6968

Discussion

In his revision of the South American Loxosceles species, Gertsch (1967) proposed four species groups for the thirty species he recognized. The only group with a single species is amazonica with the species L. amazonica described in the same paper (Gertsch 1967). This author approximated L. amazonica to the gaucho group due to the carapace marked with dark lateral bands and some incrassated segments of male palps. On the other hand, the presence of spermathecae with free receptacles with rounded lobes, not closely tied by a transverse band, resembles laeta species (Gertsch 1967). Despite L. amazonica having characteristics of both South American groups gaucho and laeta, in some genitalic features it closely resembles species of the rufescens group from the Paleartic fauna (Gertsch 1967). Due to these special characteristics, L. amazonica was considered to have group status by Gertsch (1967).

After Gertsch’s revision (1967), only scattered descriptions of new species of Loxosceles were published. A more embracing work was done by Binford et al. (2008), which proposed the first phylogenetic relationship hypothesis concerning representative Loxosceles species. In that work, besides morphological similarity, a molecular proximity was detected between L. amazonica and L. rufescens (Binford et al. 2008). The ubiquitous species L. rufescens, associated or not with the Chinese species L. lacta, was presented as the sister-group of L. amazonica in analyses with different types and combinations of datasets (Binford et al. 2008). The authors considered two possible explanations for the strong evidence of a close relationship between these species. In one explanation, the rufescens lineage would be old, with the ancestors of both species pre-dating the split of the continents; in the other, the lineage would be younger and it was suggested to be a natural dispersion from South America to Africa after the continent split occurred. According to the authors, the great genetic divergence found between L. amazonica and L. rufescens and the species diversity of the rufescens group in the Old World makes the human-mediated transportation explanation unlikely (Binford et al. 2008). However, the divergence date between L. amazonica and L. rufescens estimated by Binford et al. (2008) is too young for the presence of the most recent ancestor on Gondwana. Binford et al. (2008) also stated that the current range of L. amazonica and L. rufescens, northeastern South America and North Africa respectively, is compatible either with the Gondwana ancestor explanation or with dispersal through temporary land corridors after continental split. Thus, the distinction between ancient vicariance and more recent dispersion to explain the relationship of both species would require the inclusion of more species of these related areas in a more extensive analysis (Binford et al. 2008).

A more detailed study of the diversity of the northwestern African Loxosceles species and new molecular phylogenetic analyses including L. rufescens and L. amazonicawas done by Duncan et al. (2010). Once again, L. amazonica was recovered in the clade including the northwestern African Loxosceles species. However, there was no agreement that L. amazonica was the sister-group of the monophyletic L. rufescens lineage nor the basal taxa of the northwestern African clade. The lack of resolution inside the northwestern African clade, the existence of African male specimens very similar morphologically to L. amazonica and the fact that the most recent common ancestor of L. amazonica and L. rufescens was found by Binford et al. (2008) to be too young to be explained by Gondwanan vicariance were considered by Duncan et al. (2010) to indicate that L. amazonica is derived from within northwest Africa Loxosceles and dispersed recently from one continent to other. They proposed that the split of the continents did not influence the distribution of the common ancestor L. amazonica and L. rufescens (Duncan et al. 2010). They considered L. amazonica as a species that can be easily introduced by human transport and suggested the trade between Brazil and Africa in 16th century could explain the dispersal of L. amazonica from Africa to South America (Duncan et al. 2010). They also considered the absence of other species related to L. amazonica in South America as further evidence supporting an African origin of this species.

The discovery of two new species, herein described, closely related to L. amazonica in northwestern Brazil, throw a new light on this discussion. It is very unlikely that L. amazonica came from Africa about 500 years ago and in so little time speciated into two more different species. Another point that contradicts the argument that L. amazonica was introduced in South America is the large distribution of the species (Fig. 78). It is very improbable that such a reclusive spider would disperse to many natural localities throughout northwestern Brazil in such a short period of time, reaching remote localities in central western Brazil such as the type locality, an indigenous village difficult to access even nowadays. Furthermore, specimens of L. amazonica as well specimens of L. willianilsoni sp. n. and L. muriciensis sp. n. were found in natural environments (Figs 39–47, 66) inside and outside four Conservation Units in three Brazilian states. Moreover, if L. amazonica is an invasive species as proposed by Duncan et al. (2010), their presence in larger cities in southeastern and southern Brazil would also be expected, as invasive species are normally introduced by means of human activities and benefited by urban environments, normally forming large populations. Even though they can be found in disturbed environments in northwestern Brazil, they are found in natural conditions and are not found in urban areas in localities more to the South.

The question on the origin of L. amazonica and L. rufescens lineages is, therefore, open to discussion. A way to test the origin and evolution of L. amazonica lineage would be to collect L. amazonica specimens from different parts of northern, northwestern and central western Brazil as well as other South American countries, and determine the genetic divergence among the different populations.

As demonstrated by Duncan et al. (2010), the amazonica group is recovered in the middle of rufescens lineage. Therefore, it makes no sense to use the group name amazonica, and L. amazonica, L. willianilsoni sp. n. and L. muriciensis sp. n. should be referred as belonging to rufescens group.

Acknowledgements

We thank Adriano Kury and Carla Barros (MNRJ), Lorenzo Prendini and Lou Sorkin (AMNH) for the loan of specimens under their care. ICMBio, Jaílton J. F. Fernandes (EE Murici), George Stepherson Batista (ESEC Seridó), Mauro Guimarães dos Anjos (FLONA de Açu), Mrs. Cleíse and family from Martins (RN) are thanked for allowing collecting activities; Katie C. T. Riciluca, Nícolas M. Gonçalves, Willianilson Pessoa, Alessandro P. L. Giupponi, Luan Monteiro, Diego Ortega, Roberto H. Nagahama and Francisco Félix da Silva for helping in field work; Denis R. Pedroso for collecting specimens; Lia Aguiar for helping in expedition organization, Adrian Garda for his support on field work, Wilmar Dias da Silva and CAPES 23038.00814/2011-83 for financial support. CNPq research fellow and FAPESP 2012/01093-0 and 2015/19976-3 for RB.

References

  • Azevedo R, Texeira PMS, Siqueira RCL, Brescovit AD (2014) New record and distribution of Loxosceles amazonica Gertsch, 1967 (Araneae: Sicariidae) in the state of Ceará, Brazil. Check List 10(1): 207–208. https://doi.org/10.15560/10.1.207
  • Binford GJ, Callahan MS, Bodner MR, Rynerson MR, Nuñez PB, Ellison C, Duncan R (2008) Phylogenetic relationships of Loxosceles and Sicarius spiders are consistent with western Gondwanan vicariance. Molecular Phylogeny and Evolution 49: 538–553. https://doi.org/10.1016/j.ympev.2008.08.003
  • Brignoli PM (1969) Note sugli Scytodidae d’Italia e Malta (Araneae). Fragmenta Entomologica 6: 121–166.
  • Dufour L (1820) Descriptions de cinq arachnides nouvelles. Annales Générales des Sciences Physiques 5: 198–209.
  • Duncan RP, Rynerson MR, Ribera C, Binford GJ (2010) Diversity of Loxosceles spiders in northwestern Africa and molecular support for cryptic species in the Loxosceles rufescens lineage. Molecular Phylogenetics and Evolution 55: 234–248. https://doi.org/10.1016/j.ympev.2009.11.026
  • Ferreira RL, Prous X, Berbardi LFO, Souza-Silva M (2010) Fauna Subterrânea do Estado do Rio Grande do Norte: caracterização e impactos. Revista Brasileira de Espeleologia 1: 25–51.
  • Gertsch WJ, Ennik F (1983) The spider genus Loxosceles in North America, Central America, and the West Indies (Araneae, Loxoscelidae). Bulletin of the American Museum of Natural History 175: 264–360. http://digitallibrary.amnh.org/handle/2246/981
  • Lowe RT (1832) Descriptions of two species of Araneidae, natives of Madeira. The Zoological Journal 5: 320–323.
  • Lucas S, Cardoso JL, Moraes AC (1986) Loxoscelismo: Relato de um acidente humano atribuído a Loxosceles amazonica Gertsch, 1967 (Araneae, Scytodidae, Loxoscelinae). Memórias do Instituto Butantan 47/48: 127–131.
  • Millot J (1941) Les araignées de l’Afrique Occidentale Française - sicariides et pholcides. Mémoires de l’Académie des Sciences de l’Institut de France 64: 1–53.
  • Nemésio A, Santos Junior JE (2014) Is the “Centro de Endemismo Pernambuco” a biodiversity hotspot for orchid bees? Brazilian Journal of Biology 74(3): 78−92. doi: http://dx.doi.org/10.1590/1519-6984.26412
  • Planas E, Ribera C (2015) Description of six new species of Loxosceles (Araneae: Sicariidae) endemic to the Canary Islands and the utility of DNA barcoding for their fast and accurate identification. Zoological Journal of the Linnean Society 174: 47–73. https://doi.org/10.1111/zoj.12226
  • Ruiz-Esparza JM (2009) Influência de um brejo de altitude sobre as características da avifauna da caatinga (Serra da Guia, Sergipe e Bahia). Anais do III Congresso Latino Americano de Ecologia, São Lourenço (Brazil), September 2009. Sociedade Brasileira de Ecologia, 1–3.
  • Silveira AL (2015) Novos registros geográficos da aranha-marrom Loxosceles amazonica Gertsch, 1967 (Araneae, Sicariidae) no Nordeste do Brasil e sua importância médica. Revista Médica de Minas Gerais 25(1): 37–45. https://doi.org/10.5935/2238-3182.20150008
  • Varella-Freire AA (2002) A Caatinga Hiperxerófila Seridó, a sua caracterização e estratégias para a sua conservação. Academia de Ciências do Estado de São Paulo & U.S. Fish and Wildlife Service; São Paulo, 39 pp.
  • Wang JF (1994) Two new species of spiders of the genus Loxosceles from China. Journal of Hebei Normal University 1994(nat. Sci. Ed., Suppl.): 13–15.
  • World Spider Catalog (2016) World Spider Catalog. Natural History Museum Bern, Bern. http://wsc.nmbe.ch [version 18.0, accessed on November 2016]
login to comment