Diguetia, Simon, 1895

Jimenez, Maria-Luisa, Cardiel, Carlos Palacios & Chamé-Vázquez, David, 2022, The spider genus Diguetia Simon, 1895 (Araneae: Diguetidae) in North America a new species, redescriptions, and comments on the distribution of the genus, Zootaxa 5205 (2), pp. 125-146 : 143-144

The genus Diguetia in North America

We reviewed 313 locality records of Diguetia of North America, but 31 were discarded because we could not locate them with the original data. Furthermore, all specimen records of D. canities mulaiki Gertsch, 1958 are under D. canities , because this subspecies is probably a junior synonym of the nominate species due to minor morphological differences (see Gertsch 1958: 12–13).

The genus Diguetia has a wide distribution in North America, mainly in the arid zones, from the Mojave Basin and Range (Nevada, US) to the north, to the Balsas depression (Guerrero, Mexico) to the south ( Figs 109–110 , 113–114 ). Diguetia canities has the widest latitudinal distribution in North America ( United States and Mexico), followed by D. propinqua , D. albolineata , and D. imperiosa ( Figs 109–110 ). In contrast, D. mojavea seems restricted to the Mojave and Sonoran Desert, while Diguetia dialectica stat. reval., D. stridulans , and D. balandra sp. nov. seem to be endemic species of the Baja California Peninsula ( Figs 109–110 ). This Peninsula harbors several dozens of endemics species as a consequence of the isolated geographic process of rifting and separation from the Mexican mainland 5.5 Ma ago ( Riddle et al. 2000; González-Trujillo et al. 2016), as well as later geological events (3–1 million years) and climatic changes of the Pleistocene-Holocene ( Riddle et al. 2000; Hafner & Riddle 2005; Garrick et al. 2013).

Furthermore, Diguetia canities (47.1%), D. signata (16.3%), and D. imperiosa (12.4) have the greatest number of records in North America, while D. andersoni , D. balandra sp. nov. and D. stridulans had the lowest number of records ( Fig. 111 ). The ecoregions with most records of Diguetia , in decreasing order, are the Sonoran Desert, Chihuahuan Desert, Madrean Archipelago, California Coastal Sage, Chaparral, and Oak Woodlands, Arizona / New Mexico Mountains, Mojave Basin and Range, and Baja Californian Desert ( Fig. 112 ). The principal climates of such ecoregions are dry desert, dry subtropical steppe, and Mediterranean climates. The most common vegetation includes large areas of cacti, chaparral, shrub-steppe, arid shrublands, desert grasslands, and patches of oak and pine woodlands at higher elevations. Most ecoregions (level III) with records of Diguetia are nested within North American Deserts, Temperate Sierras, and Great Plains ecoregions (level I) ( Fig. 112 ).

Southwestern states of the US and northwestern of Mexico have high richness of species, especially California and Sonora with five species each. This richness decreases to the east and south; for example, Tamaulipas and Guerrero ( Mexico) have one and two species respectively ( Fig. 113 ). In North America, the Sonoran ecoregion (level III) have the highest richness of species of Diguetia with six species, followed by the Chihuahuan Desert and Mediterranean California ecoregions with five species each ( Fig. 114 ). Moreover, Diguetia species can be found from sea level to high elevations (10–2,731m). The following species have a broad altitude range: D. canities (20–2,731m), D. albolineata (10–2,451m), D. propinqua (515–2,451m), D. imperiosa (32–1,966m), and D. signata (10–1,915m).

Diguetia imperiosa is here recorded for the first time in Baja California Sur. Diguetia signata , previously known from Arizona, California, and Nevada ( U.S. A), is recorded from xeric shrub habitats of Baja California Sur and Chihuahua ( Mexico) ( Table 1 , Fig. 110 ). We could not examine the female type of D. stridulans Chamberlin, 1924 , but to our knowledge the type is in poor condition (see Gertsch 1958), and the male is still unknown. In our opinion, a reexamination of the genitalic morphology of broadly distributed species is needed because it could reveal cryptic species. Moreover, the diversity of the genus could be higher because large areas within the known distribution of North American diguetids remain undersampled.

Figures

FIGURES 109–110. Records of North American Diguetia species.

FIGURES 111–114. 111. Percent proportion of Diguetia records (282 records) by species from North America. 112. Percent proportion of Diguetia records by level III ecoregions (outer ring) nested by ecoregions level I (inner circle). 113. Number of species by Mexican or US states. 114. Number of species by North American level III ecoregions (sensu U.S. Environmental Protection Agency 2013).