Aphonopelma bacadehuachi, Hendrixson, 2019

Hendrixson, Brent E., 2019, A new species of Aphonopelma (Araneae: Mygalomorphae: Theraphosidae) from the Madrean pine-oak woodlands of northeastern Sonora, Mexico, Zootaxa 4688 (4), pp. 519-534 : 526-530

Aphonopelma bacadehuachi sp. nov.

( Figures 3–21 )

urn:lsid:zoobank.org:act:FB8FFD04-A9E2-4DFA-9D1C-F92C98558297

Type series. MEXÍCO: Sonora: ♂ holotype (APH-1357) and ♀ paratype (APH-1356) collected from Municipio de Bacadéhuachi, Rincón de Guadalupe, 14.9 km (by air) ENE of Bacadéhuachi , Arroyo Campo los Padres ( Rio Riito drainage), Sierra de Bacadéhuachi (N29.84806°, W108.99417°, 1800 m) on 2 August 2011 by Thomas R. Van Devender. Deposited at UIM .

Etymology. The specific epithet is a noun in apposition taken from the type locality in Sierra de Bacadéhuachi, the westernmost range of the Sierra Madre Occidental in Sonora, Mexico.

Diagnosis. Aphonopelma bacadehuachi belongs to the Marxi species group ( Hamilton et al. 2016) and is most closely related to the four MSI species from Arizona and New Mexico: A. catalina , A. chiricahua , A. madera , and A. peloncillo ( Fig. 2 ).

The following combination of characteristics when considered together will facilitate identification of A. bacadehuachi : medium- to large-sized tarantulas (carapace length of holotype male = 13.87, paratype female = 17.00) with black (males) or gray (females) pubescence on the carapace and bright orange-red setae on the opisthosoma ( Figs. 3 & 4 ); prolateral surface of coxa I with a mix of fine hair-like setae and numerous tapered setae (not spinoid) with swollen bases. Compared to the other MSI species, A. bacadehuachi possesses the following unique COX1 nucleotides: A (pos 90), C (pos 283), G (pos 435), A (pos 567), C (pos 618), C (pos 630), C (pos 792), A (pos 837), G (pos 852), A (pos 855). The reference alignment for comparative purposes is available upon request (also see Bond 2004; Bond & Stockman 2008; Satler et al. 2013 for molecular diagnoses of other mygalomorph taxa).

Comparisons. The male holotype of A. bacadehuachi is distinctly separate from males of the MSI species in PCA morphospace ( Fig. 1 ). It can be separated from these species based on the following non-overlapping measurements and morphometric ratios (values for A. bacadehuachi listed first): from A. catalina , CL (13.87, 9.57–12.39), F1L/F1W (4.06, 5.03–5.33), F3L/F3W (3.21, 3.61–3.80), F4L/F4W (3.77, 4.64–4.79); from A. chiricahua , CL (13.87, 6.84 – 11.42), CL/M4 (0.90, 1.02 – 1.19), L3L/CL (3.43, 2.98–3.18); from A. madera , CL (13.87, 7.82– 9.43), L3L/CL (3.43, 2.71–2.95), L4L/CL (4.16, 3.34–3.86); from A. peloncillo , CL/T1 (0.96, 1.02–1.10), L3L/CL (3.43, 3.05–3.22), L4L/CL (4.16, 3.77–4.01).

The female paratype of A. bacadehuachi is not well separated from most females of the MSI species in PCA morphospace ( Fig. 1 ) but this is not unusual for females of some closely related mygalomorph species (e.g., Bond 2004; Bond & Stockman 2008). As a result, no meaningful morphometric ratios were found that distinguish the female paratype from females of the other MSI species; however, raw measurements obtained from the female paratype are consistently larger than those reported for females of A. catalina , A. chiricahua , and A. madera in Hamilton et al. (2016) .

Only one species in Mexico has been reported from the general vicinity of A. bacadehuachi . Smith (1995) described A. mooreae Smith from Yécora near the Sonora / Chihuahua border, approximately 160 km south of the type locality for A. bacadehuachi . Based on information gathered from iNaturalist (https://www.inaturalist.org/ observations?taxon_id=264079) and other online sources (e.g., https://www.desertmuseum.org/programs/alamos_ fauna_montane.php) (links accessed 16 March 2019), A. mooreae is a denizen of the pine-oak woodlands of the northern Sierra Madre Occidental and may be closely related to the MSI species. Aphonopelma bacadehuachi is readily distinguished from A. mooreae by its less flamboyant color pattern (i.e., males and females of A. mooreae are clothed with metallic green and/or blue pubescence on the carapace and legs) and has been found with a more northern distribution in the Sierra Madre Occidental ( Fig. 22 ).

Smith (1995) also described A. levii Smith from a pine-oak woodland locale in the Sierra Madre Occidental near the Durango/Sinaloa border, more than 750 km south-southeast of the type locality for A. bacadehuachi . The male holotype of A. levii (Natural History Museum, London, United Kingdom, not examined) was described as having “fawny orange pubescence” on the carapace, a condition markedly different from the black pubescence found on the carapace of the male holotype of A. bacadehuachi .

Remarks. The breeding period for theraphosid spiders is defined as the period of time when adult males abandon their retreats and actively wander in search of prospective mates ( Prentice 1997). In temperate North America, male activity is fairly predictable and most species in the US have been categorized as either summer or fall breeders even though overlap between the two occurs on occasion ( Prentice 1997; Hendrixson et al. 2015; Hamilton et al. 2016). Despite the small number of samples available for this study (n = 1 male), it is not unreasonable to conclude that A. bacadehuachi is a summer breeder ( A. catalina , A. chiricahua , and A. madera are fall breeders) based on when the male holotype was collected in early August 2011. The specimen’s body condition suggests that he matured and became active in June or July. Previous field observations indicate that mature males of A. catalina , A. chiricahua , and A. madera do not become active until October or later ( Hendrixson et al. 2015; M. Jacobi pers. comm. 2018) so this temporal information also appears useful for distinguishing A. bacadehuachi from these MSI species. But even if the breeding periods for A. bacadehuachi and these MSI species are eventually found to overlap during the late summer/early fall, it should not preclude the use of “summer versus fall breeding period” as a useful feature for distinguishing different species. My observations of Aphonopelma in southern Arizona indicate that males of summer breeding species (e.g., A. chalcodes and A. vorhiesi ) are generally in poor condition (i.e., faded coloration, worn-down or missing appendages, shrunken abdomen, reduced pubescence/setation on carapace and appendages, bald urticating bristle patch, lethargy) whereas males of fall breeding species (e.g., A. madera ) are vigorous and vibrant in color during these brief periods of overlap; this information can facilitate categorizing the breeding period for unknown species and can be used to distinguish closely related species.

Accurate identification of Aphonopelma species using morphology is challenging at best but virtually impossible in the absence of supporting data. Identification of preserved museum material—especially females and immature specimens—is problematic due to uninformative morphology, faded coloration, inability to assess breeding periods, and lack of high-quality genetic data. This problem is exacerbated in regions that have been poorly sampled. Hamilton et al. (2016) assigned species status to hundreds of museum specimens but only after comparing them to an extensive collection of freshly gathered samples that were accompanied by precise locality information (including coordinates, collection dates, habitat descriptions), photographs (for assessing coloration and body condition), and genetic data. Such data are not available for Aphonopelma species in northern Mexico. As a result, the diagnosis for A. bacadehuachi is most applicable to freshly collected specimens. In the case of females and immature specimens, COX1 sequences—albeit not the most practical or accessible—are best for identification at this time.

Description of male holotype (APH-1357, Figs. 3 , 5–15 ). Specimen preparation and condition: specimen found live, preserved in 80% ethanol; original coloration faded due to preservation; legs and pedipalps removed for measurements and digital imaging (stored with specimen); left pedipalp bulb placed in shell vial (stored with specimen); left leg III removed for DNA and stored at -80°C at Millsaps College (Jackson, Mississippi, USA).

Prosoma ( Fig. 5 ): CL 13.87, CW 14.71; carapace densely clothed with black/faded black pubescence, appressed to surface; fringe covered in long setae not closely appressed to surface; foveal groove medium-deep and slightly procurved; pars cephalica region rises gradually from foveal groove, gently arching anteriorly toward ocular region; AER procurved, PER recurved; normal-sized chelicerae (not especially robust); clypeus straight; LBL 1.99, LBW 2.48; sternum hirsute, densely clothed with short black and straw-colored setae.

Opisthosoma ( Fig. 3 ): densely clothed with short black setae interspersed with numerous longer, more lightlycolored setae (generally orange to red in life); dense dorsal patch of Type I urticating bristles; ventral setae same as dorsal.

Legs ( Fig. 3 ): hirsute, densely clothed with short black setae and longer straw-colored setae dorsally; F1 16.19, F1 W 3.99, P1 6.07, T1 14.47, M1 10.36, A1 6.77, L1L 53.86, F3 13.11, F3 W 4.09, P3 4.95, T3 10.35, M3 11.60, A3 7.61, L3L 47.62, F4 15.15, F4 W 4.02, P4 5.43, T4 13.17, M4 15.36, A4 8.55, L4L 57.66; prolateral surface of coxa I clothed with mix of fine hair-like setae and numerous tapered setae with swollen bases; 1 large megaspine on retrolateral surface of tibia I near apex of mating clasper; prolateral and ventral branches of tibial apophysis both possess a large anteriorly-projecting megaspine ( Figs. 6, 7 ); femur III normal, not noticeably swollen or wider than other legs ( Fig. 12 ); all tarsi fully scopulate, Sc3 0.587 ( Fig. 8 ), Sc4 0.378 ( Fig. 9 ); 5 and 7 distal spinose setae on metatarsi III and IV, respectively.

Pedipalps ( Figs. 10 & 11 ): hirsute, densely clothed with short black and longer straw-colored setae, with numerous long ventral setae; 1 prolateral spinose seta at apical end of femur; 1 spinose seta located distoventrally on tibia; PTL 8.31, PTW 3.71; embolus tapers with gentle retrolateral curve toward apex ( Figs. 13–15 ); embolus slen- der, lacking distinct carinae.

COX1 barcode sequence: MN428548 .

Description of female paratype (APH-1356, Figs. 4 , 16–21 ). Specimen preparation and condition: specimen found recently after death (cause unknown), preserved in 80% ethanol; original coloration faded due to preservation; right legs and pedipalp removed for measurements and digital imaging (stored with specimen); genital plate and spermathecae removed and placed in shell vial (stored with specimen); left leg III removed for DNA and stored at -80°C at Millsaps College (Jackson, Mississippi, USA).

Prosoma ( Fig. 16 ): CL 17.00, CW 16.10; carapace densely clothed with gray pubescence, appressed to surface; fringe covered in long setae not closely appressed to surface; foveal groove medium-deep and straight; pars cephalica region rises gradually from foveal groove, arching anteriorly toward ocular region; AER procurved, PER straight; robust chelicerae (especially compared to male); clypeus mostly straight; LBL 2.27, LBW 2.80; sternum hirsute, densely clothed with short black and straw-colored setae.

Opisthosoma ( Fig. 4 ): densely clothed with short black setae interspersed with numerous longer, more lightlycolored setae (generally orange to red in life); dense dorsal patch of Type I urticating bristles; ventral setae same as dorsal; spermathecae ( Fig. 19 ) paired and separate, tapering and slightly curving medially toward capitate bulbs, with wide bases that appear fused.

Legs ( Fig. 4 ): hirsute, densely clothed with short black setae and longer straw-colored setae dorsally; F1 14.72, F1 W 4.89, P1 6.22, T1 11.10, M1 7.98, A1 6.63, L1L 46.65, F3 11.21, F3 W 4.41, P3 5.33, T3 8.48, M3 8.71, A3 6.51, L3L 40.24, F4 14.20, F4 W 4.53, P4 5.67, T4 11.00, M4 12.58, A4 7.46, L4L 50.91; prolateral surface of coxa I clothed with mix of fine hair-like setae and numerous tapered setae with swollen bases ( Fig. 18 ); all tarsi fully scopulate, Sc3 0.647 ( Fig. 20 ), Sc4 0.387 ( Fig. 21 ); 7 and 8 distal spinose setae on metatarsi III and IV, respectively.

Pedipalps ( Fig. 17 ): hirsute, densely clothed with short black and longer straw-colored setae, with numerous long ventral setae; 4 distal spinose setae on tibia; PTL 7.68, PTW 2.84.

COX1 barcode sequence: MN428547 .

Variation. Aphonopelma bacadehuachi is known only from a single male and female specimen.

Distribution and natural history. Aphonopelma bacadehuachi is known only from the type locality in the Sierra de Bacadéhuachi in northeastern Sonora, Mexico ( Fig. 22 ). The holotype and paratype were both collected at approximately 1,800 meters elevation from a rocky canyon and mountainside. Vegetation at the collection site is characterized as typical Madrean pine-oak woodland along the slopes with a sycamore-Arizona cypress riparian area along the canyon floor (T. Van Devender pers. comm. 2011).

Aphonopelma bacadehuachi appears to be a summer breeder based on when the male holotype was collected in early August 2011.

Comparative type material examined. Aphonopelma catalina [♂ holotype (APH-1440) and ♀ paratype (APH-1602)]; Aphonopelma chiricahua [♂ holotype (APH-3191) and ♀ paratype (APH-2097)]; Aphonopelma madera [♂ holotype (APH-3177) and ♀ paratype (APH-1393)]; Aphonopelma peloncillo [♂ holotype (APH-0672) and ♀ paratype (APH-1296)]. Specific collection information can be found in Hamilton et al. (2016); all specimens at UIM.

Figures

FIGURE 1. Scatterplot of principal components for measurements of mature male (top) and female (bottom) Madrean Aphonopelma species. Percentage values indicate the proportion of variation explained by a particular principal component (PC1 and PC2).

FIGURE 2. Maximum likelihood phylogeny of the Madrean members of the Marxi species group based on COX1 mtDNA. For presentation sake, specimen labels have been removed from the tree tips. Numbers along branches indicate maximum likelihood bootstrap support values. Photograph is an adult male Aphonopelma madera from the Huachuca Mountains in southeastern Arizona.

FIGURE 22.Map of the southwestern United Statesand northwestern Mexico showingthe distributions of the Madrean members of the Marxi species group and Aphonopelma mooreae. The localities for A. mooreae are based on reports provided in iNaturalist (https://www.inaturalist.org/observations?taxon_id=264079, accessed 16 March 2019). The distribution for A. peloncillo only reflects specimens from the eastern foothills of the Peloncillo Mountains and the Animas Valley in New Mexico and does not include several specimens outside of this area as reported in Hamilton et al. (2016); further research is necessary to confirm the identity of the latter specimens. State abbreviations: AZ = Arizona, NM = New Mexico, SON = Sonora, CHI = Chihuahua. The Madrean pine-oak woodlands shapefile was “exploded” from a larger shapefile depicting the planet’s biodiversity hotspots (downloaded from http://legacy.cepf.net/SiteAssets/hotspots_2016_1.zip, accessed 16 March 2019).

FIGURE 3–4. Dorsal habitus of Aphonopelma bacadehuachi, sp. nov. from Sonora, Mexico. 3, male holotype (APH-1357); 4, female paratype (APH-1356). Scale bar = 20 mm.

FIGURES 5–15. Morphology of Aphonopelma bacadehuachi, sp. nov. from Sonora, Mexico (male holotype, APH-1357). 5, carapace, dorsal view; 6, patella and tibia of left leg I, prolateral view; 7, tibial apophysis of left leg I, prolateral view; 8, metatarsus and tarsus of left leg III, ventral view; 9, metatarsus and tarsus of left leg IV, ventral view; 10, left pedipalp, retrolateral view; 11, left pedipalp, prolateral view; 12, femur of leg III, dorsal view; 13, palpal bulb, prolateral view; 14, palpal bulb, retrolateral view; 15, palpal bulb, dorsal view. Scale bar = 5 mm (except for palpal bulb and illustration of tibial apophysis, scale bar = 2 mm).

FIGURES 16–21. Morphology of Aphonopelma bacadehuachi, sp. nov. from Sonora, Mexico (female paratype, APH-1356). 16, carapace, dorsal view; 17, right pedipalp, prolateral view; 18, coxa of right leg I, prolateral view; 19, spermathecae; 20, metatarsus and tarsus of left leg III, ventral view; 21, metatarsus and tarsus of left leg IV, ventral view. Scale bar = 5 mm (except for spermathecae, scale bar = 2 mm).