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. 2019 Nov 27:892:93-133.
doi: 10.3897/zookeys.892.39558. eCollection 2019.

Under an integrative taxonomic approach: the description of a new species of the genus Loxosceles (Araneae, Sicariidae) from Mexico City

Alejandro Valdez-Mondragón  1   2 , Claudia I Navarro-Rodríguez  3   4 , Karen P Solís-Catalán  3   4 , Mayra R Cortez-Roldán  3 , Alma R Juárez-Sánchez  3
Affiliations

Under an integrative taxonomic approach: the description of a new species of the genus Loxosceles (Araneae, Sicariidae) from Mexico City

Alejandro Valdez-Mondragón et al. Zookeys. .

Abstract

A new species of the spider genus Loxosceles Heineken & Lowe, 1832, Loxosceles tenochtitlan Valdez-Mondragón & Navarro-Rodríguez, sp. nov., is described based on adult male and female specimens from the states of Mexico City, Estado de Mexico and Tlaxcala. Integrative taxonomy including traditional morphology, geometric and lineal morphology, and molecules (DNA barcodes of cytochrome c oxidase subunit 1 (CO1) and internal transcribed spacer 2 (ITS2)), were used as evidence to delimit the new species. Four methods were used for molecular analyses and species delimitation: 1) corrected p-distances under neighbor joining (NJ), 2) automatic barcode gap discovery (ABGD), 3) general mixed yule coalescent model (GMYC), and 4) poisson tree processes (bPTP). All molecular methods, traditional, geometric and lineal morphology were consistent in delimiting and recognizing the new species. Loxosceles tenochtitlan sp. nov. is closely related to L. misteca based on molecular data. Although both species are morphologically similar, the average p-distance from CO1 data was 13.8% and 4.2% for ITS2 data. The molecular species delimitation methods recovered well-supported monophyletic clusters for samples of L. tenochtitlan sp. nov. from Mexico City + Tlaxcala and for samples of L. misteca from Guerrero. Loxosceles tenochtitlan sp. nov. is considered a unique species for three reasons: (1) it can be distinguished by morphological characters (genitalic and somatic); (2) the four different molecular species delimitation methods were congruent to separate both species; and (3) there is variation in leg I length of males between both species, with the males of L. misteca having longer legs than males of L. tenochtitlan sp. nov., also morphometrically, the shape of tibiae of the palp between males of both species is different.

Keywords: DNA barcodes; Loxosceles tenochtitlan sp. nov.; ecological niche modeling; species delimitation; taxonomy.

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Figures

Figures 1–6.
Figures 1–6.
Live specimens of Loxosceles tenochtitlan sp. nov. from Street Juárez Norte #214, Huamantla, Municipality Huamantla, Tlaxcala, Mexico 1–3 females 4–6 males. Photographs by Jared Lacayo-Ramírez (2019).
Figures 7–13.
Figures 7–13.
Live female specimens of the Loxosceles tenochtitlan sp. nov. from Street Cruz Verde #132, Tlalpan, Mexico City, Mexico (type locality). Red arrows indicate specific places where the specimens were collected inside the house. Photographs by Martín Sánchez Vílchis (2019).
Figures 14–18.
Figures 14–18.
Live specimens and urban microhabitat of Loxosceles tenochtitlan sp. nov. from Tlaxcala 14–17 specimens from Street Juárez Norte #214, Huamantla downtown, Municipality, Huamantla, Tlaxcala, Mexico 18 microhabitat where some specimens were collected from Street Reforma #5, Santiago Tlacochcalco, Municipality Tepeyanco, Tlaxcala, Mexico. Red arrows indicate the specific places where specimens were collected. Photographs 14–17 by José A. Castilla-Vázquez (2018–2019). Photograph 18 by Alma R. Juárez-Sánchez (2018).
Figures 19–22.
Figures 19–22.
Loxosceles tenochtitlan sp. nov 19–20 habitus of male holotype, dorsal and ventral views, respectively 21–22 habitus of female paratype, dorsal and ventral views, respectively. Scale bars: 1 mm.
Figures 23–28.
Figures 23–28.
Loxosceles tenochtitlan sp. nov. Male Holotype 23–25 left palp, prolateral, dorsal and retrolateral views respectively 26–28 detail of the bulb and embolus, dorsal, retrolateral and apical views, respectively. Scale bars: 0.5 mm (23–25), 0.2 mm (26–28).
Figures 29–34.
Figures 29–34.
29–31Loxosceles misteca Gertsch. Male 29 left palp, retrolateral view, detail of tarsus, bulb and embolus 30 detail of bulb and embolus, retrolateral view 31 detail of the embolus 32–34Loxosceles tenochtitlan sp. nov. Male paratype 32 right palp, retrolateral view, detail of tarsus, bulb and embolus 33 detail of bulb and embolus, retrolateral view 34 detail of the embolus. Arrows indicate the canal along the embolus.
Figures 35–37.
Figures 35–37.
Loxosceles tenochtitlan sp. nov. Male paratype 35 right palp, tarsus, bulb and embolus, dorsal view 36 right palp, retrolateral view 37 detail of the canal along the embolus.
Figures 38–41.
Figures 38–41.
Male holotype (examined) of Loxosceles misteca Gertsch, 1958 (AMNH_IZC 00327631), from Taxco, Municipality Taxco de Alarcón, Guerrero, Mexico; Date? 1946, collected in the fall, Leo Isaacs leg. 38, 39 habitus of male holotype, dorsal and ventral views, respectively 40 carapace 41 label of the holotype. Scale bars: 1 mm (38–40).
Figures 42–47.
Figures 42–47.
Male holotype (examined) of Loxosceles misteca Gertsch, 1958 (AMNH_IZC 00327631), from Taxco, Municipality Taxco de Alarcón, Guerrero, Mexico; 1946, collected in the fall, Leo Isaacs leg. 42–44 left palp, prolateral, dorsal and retrolateral views respectively 45–47 detail of the bulb and embolus, dorsal, retrolateral and apical views, respectively. Scale bars: 0.5 mm (42–44), 0.2 mm (45–47).
Figures 48–55.
Figures 48–55.
Loxosceles tenochtitlan sp. nov. Variation of the male palps, left palps, prolateral views 48 turiello Guerra, Street Cuitlahuac S/N, Tlalpan, Mexico City 49 Cruz Verde #132, Tlalpan, Mexico City (type locality) 50 Street Tepocatl #61, Pedregal de Santo Domingo, Coyoacán, Mexico City 51 Los Reyes Copilco, Frac. Areada Dpto. 102-A, Coyoacán, Mexico City 52, 53 Street Reforma #5, Santiago Tlacochcalco, Municipality of Tepeyanco, Tlaxcala 54, 55 Street Juárez Norte #214, Huamantla, Municipality Huamantla, Tlaxcala, Mexico. Scale bars: 0.5 mm.
Figures 56–61.
Figures 56–61.
Loxosceles tenochtitlan sp. nov. Variation of the seminal receptacles of the females, dorsal views 56 Street Cruz Verde #132, Tlalpan, Mexico City (type locality) (female paratype) 57 Los Reyes Copilco, Fracc. Areada Dpto. 102-A, Coyoacán, Mexico City 58 Street Juárez #23, San Mateo Ixtacalco, Municipality Cuautitlán Izcalli, Estado de Mexico 59 Street Reforma #5, Santiago Tlacochcalco, Municipality of Tepeyanco, Tlaxcala 60, 61 Street Juárez Norte #214, Huamantla, Municipality of Huamantla, Tlaxcala, Mexico.
Figures 62–69.
Figures 62–69.
Loxosceles misteca Gertsch, 1958 62–65 variation of the male palps, left palps, prolateral views 62 Grutas General Carlos Pacheco, Municipality Pilcaya, Guerrero 63 Cueva del Diablo Acuitlalpan, Municipality Taxco, Guerrero 64 boulevard Cuauhtémoc #99, Colonia Lomas de Cortes, Municipality Cuernavaca, Morelos 65 Grutas de Cacahuamilpa National Park, Municipality Pilcaya, Guerrero 66–69 variation of the seminal receptacles of the females, dorsal views 66, 67 Agustin Lorenzo Cave, Mexcaltepec, Municipality Taxco de Alarcón, Guerrero 68, 69 Botanical Garden Cave, Grutas de Cacahuamilpa National Park, Municipality Pilcaya, Guerrero.
Figure 70.
Figure 70.
Neighbor-joining (NJ) tree constructed from COI data of ten species of Loxosceles from Mexico. Colors of branches indicate different species. Numbers on nodes are bootstrap support values. Red circles represent Loxosceles tenochtitlan sp. nov.
Figure 71.
Figure 71.
Neighbor-joining (NJ) tree of ITS2 data of nine species of Loxosceles from Mexico. Colors of branches indicate different species. Numbers at nodes represent bootstrap support values. Red circles represent Loxosceles tenochtitlan sp. nov.
Figure 72.
Figure 72.
Maximum likelihood tree inferred from the concatenated matrix (CO1 + ITS2) of Loxosceles species from Mexico. Colors of branches and bars indicate different species. Numbers above bars at right represent the delimitation methods: 1: morphology (M). 2: neighbor-joining (NJ). 3: ABGD with initial partitions (IP). 4: ABGD with recursive partitions (RP). 5: GMYC. 6: bPTP with ML. 7: bPTP with IB. Numbers below bars represent species recovered for each delimitation method. Red numbers correspond to Bayesian posterior probabilities, and black numbers are bootstrap support values from the ML analysis.
Figure 73.
Figure 73.
Haplotype network from the CO1 data obtained with TCS using PopArt. Each circle represents the haplotypes found in ten species of Loxosceles from Mexico. Numbers on branches indicate the number of mutations between haplotypes.
Figures 74–77.
Figures 74–77.
Geometric morphometry of the tibia shape on retrolateral view of the palps of males of L. tenochtitlan sp. nov. (N = 12) and L. misteca (N = 9) 74CVA plot showing a significant difference (χ2 = 10.2555, df = 2, p = 0.00593003, λ = 0.5988) between both species in the tibiae shape 75 deformation grid, the vectors indicate the direction of change in the tibia with respect to the average shape of the 21 individuals analyzed of both species 76, 77 palps of the males of L. misteca and L. tenochtitlan sp. nov. respectively, retrolateral views (red arrows indicate the change in the shape of the tibiae of the species analyzed).
Figures 78–81.
Figures 78–81.
Sexual dimorphism of Loxosceles tenochtitlan sp. nov. (T test) 78 box plots showing the variation of leg length 1 between males and females (t = -1.3106, p = 0.1981, df = 37, α = 0.05) 79, 80 box plots showing variation of carapace length (79) and width (80) between males and females (length: t = 1.498, p = 0.142, df = 38, α = 0.05; width: t = 0.6955, p = 0.4912, df = 36, α = 0.05) 81 linear morphometric variation of leg I length between males and females of L. tenochtitlan and L. misteca (T test) (males: t = 3.6174, p = 0.00331, df = 13, α = 0.05; females: t = 0.274, p = 0.787, df = 17, α = 0.05).
Figure 82–83.
Figure 82–83.
82 Distribution records of Loxosceles tenochtitlan sp. nov. from Mexico City (CDMX), Estado de Mexico (MEX), and Tlaxcala (TLAX) 83 known records of L. tenochtitlan sp. nov. from Mexico City, including the type locality (star).
Figures 84.
Figures 84.
Ecological niche modeling (ENM) under Maxent algorithm for Loxosceles tenochtitlan sp. nov. Colors represent different ranges of probabilities of presence (high probability: 0.75–1.0). Circles represent known records of the new species. Blue lines represent biogeographical provinces proposed by Morrone (2004, 2005).
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