Loxosceles rufescens (Dufour, 1820)

Valdez-Mondragon, Alejandro, Cortez-Roldan, Mayra R., Juarez-Sanchez, Alma R. & Solis-Catalan, Karen P., 2018, A new species of Loxosceles Heineken & Lowe (Araneae, Sicariidae), with updated distribution records and biogeographical comments for the species from Mexico, including a new record of Loxosce, ZooKeys 802, pp. 39-66: 54-57

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Loxosceles rufescens (Dufour, 1820)


Loxosceles rufescens (Dufour, 1820)  Figs 68-72

Scytodes rufescens  Dufour 1820c: 203, pl. 76, fig. 5 (male).

Loxosceles citigrada  Heineken and Lowe in Lowe (transferred) 1832: 322, pl. 48, figs 1-14 (male, female).

See World Spider Catalog (2018) for complete records.

Material examined.

MEXICO: Chihuahua: 1 male, 1 female (LATLAX-Ara0183) from Instituto de Biomédicas de la Universidad Autónoma de Ciudad Juárez (31. 74645, −106.4444; 1130 m), Municipality Ciudad Juárez, no date, P. Flores col.


L. rufescens  resembles Loxosceles foutadjalloni  Millot, 1941; in having male palpal tibia wide and a long embolus ( Lotz 2012: fig. 9C), however in L. rufescens  the male palp tibia is wider and the embolus is sigmoid-shaped (Figs 68-69), whereas in L. foutadjalloni  the embolus is long and curved ( Lotz 2012: fig. 9C). Females resemble L. foutadjalloni  by the shape of the seminal receptacles ( Lotz 2012: fig. 10B), however in L. rufescens  they are short and round distally (Fig. 70), whereas in L. foutadjalloni  the seminal receptacles are longer and distally bifurcated and rounded ( Lotz 2012: fig. 10B).


See Chomphuphuang et al. (2016).


Loxosceles rufescens  (Figs 68-72) has a natural distribution in the Mediterranean Basin and the Middle East ( Nentwig et al. 2017; Tahami et al. 2017), but also is considered a cosmopolitan species ( Nentwig et al. 2017; World Spider Catalog 2018).


In Mexico, L. rufescens  is only known from two records, from the states of Tamaulipas and Chihuahua (Fig. 73). Chickering (1937) reported L. rufescens  from San Carlos Mountains, Tamaulipas; however, he never described or illustrated any specimen, which makes his record questionable (Fig. 74).

Updated distribution records for the 39 species of Loxosceles  from Mexico.

A total of 461 records of the 39 species of Loxosceles  distributed in Mexico were reviewed. Twenty records were discarded for not having complete localities or having doubtful georeferences. Thus, a total of 441 records were used to make the distribution maps (Figs 73-76). The states with the most records are Guerrero with 55, Mo relos with 35, and Baja California Sur with 30 (Fig. 75). The state of Tabasco only has a single record (Appendix 1, Fig. 75). The most diverse states are Baja California Sur, Baja California, Sonora (with five species each), Guerrero, Tamaulipas (with four species each), and Oaxaca, Puebla, Hidalgo, Coahuila, San Luis Potosí, Nuevo León (with three species each) (Figs 73, 74). The least diverse states are Durango, Zacatecas, Michoacán, Querétaro, Chihuahua and Sinaloa (with two species each); Jalisco, Guanajuato, Quintana Roo, Colima, Chiapas, Yucatan, Campeche, Tabasco, Veracruz, Mexico City, Nayarit, Aguascalientes, Tlaxcala and state of Mexico (with a single species each) (Figs 73-76).

Regarding the number of total records per species of Loxosceles  , the species with the most records are L. boneti  with 59 and L. colima  with 57 (Fig. 75). The species with the least number of records are L. barbara  , L. carmena  , L. francisca  , L. insula  , L. luteola  and L. rufescens  with a single record each (Fig. 74). A new record of L. misteca  was found for Tlaxcala (Figs 75). A third record of L. reclusa  was found for Tamaulipas (Fig. 74). The record of L. rufescens  from Ciudad Juárez, Chihuahua represents the second record for the country of this introduced species and the first well-documented and illustrated record from Mexico (Figs 68-72, 73, Appendix 1).