Aphonopelma chiricahua Hamilton, Hendrixson & Bond, 2016

Hamilton, Chris A., Hendrixson, Brent E. & Silvestre Bringas, Karina, 2024, Discovery of a new tarantula species from the Madrean Sky Islands and the first documented instance of syntopy between two montane endemics (Araneae, Theraphosidae, Aphonopelma): a case of prior mistaken identity, ZooKeys 1210, pp. 61-98 : 61-98

Aphonopelma chiricahua Hamilton, Hendrixson & Bond, 2016

Figs 8 , 9 , 10 , 11

Aphonopelma chiricahua Hamilton et al. 2016: 90–93, 95–98, figs 37, 39.

Type material.

Holotype. United States • ♂; Arizona, Cochise County, Chiricahua Mountains, Cave Creek Canyon , 1.6 km past the Cathedral Vista Trailhead along Forest Road 42 (toward the Southwest Research Station); 31.88133 ° N, 109.18797 ° W 4; 1600 m; 14 Nov. 2013; Helen Snyder leg.; UIM; APH-3191 .

Remarks.

In the original description of A. chiricahua, Hamilton et al. (2016: 98) stated: “ Of particular note is the size of the holotype male and paratype female; the two specimens probably represent opposite extremes on the size spectrum for what is possible in this species. The rather large holotype male was chosen because it was a fresh specimen and could be associated with molecular data that was unique from all other samples in the area, at the time. The female, though small, is sexually mature (based on spermathecal development). ” Based on the body size, morphology, and collection data for the female paratype of A. chiricahua ( APH- 2097), we have determined that the specimen was misidentified and should now be considered A. jacobii sp. nov. Similarly, except for the male holotype ( APH- 3191), we have determined that the male specimens of A. chiricahua reported in Hamilton et al. (2016) were misidentified and should be considered A. jacobii sp. nov. too. Consequently, a redescription and emended diagnosis for A. chiricahua are necessary to reassess limits of morphological variation in the species. The following redescription of A. chiricahua is based on several newly acquired individuals (mature males and females) whose identities have been confirmed by comparing their COX 1 and UCE sequence data to the male holotype (Figs 1 , 2 ; unpublished data).

Emended diagnosis.

Aphonopelma chiricahua is a member of the Marxi species group and can be distinguished by a combination of morphological, genomic, behavioral, and distributional features. This species is a mid- to late-fall breeder endemic to the Chiricahua Mountains in southeastern Arizona. Mitochondrial and nuclear DNA identifies A. chiricahua as a monophyletic lineage (Figs 1 , 2 ) that is sister to A. catalina (and an undetermined species) and phylogenetically distinct from the other tarantula species endemic to the Chiricahua Mountains (i. e., A. jacobii sp. nov.). Aphonopelma chiricahua is found in oak and pine-oak woodlands where its distribution overlaps with A. chalcodes , A. gabeli , A. jacobii sp. nov., and A. vorhiesi .

For features that can be used to distinguish A. chiricahua from A. jacobii sp. nov., refer to the diagnosis of the latter species provided above. When in doubt, the identity of both species (including immature specimens) can be readily confirmed with COX 1 barcoding. Aphonopelma chiricahua is readily distinguished from A. chalcodes and A. gabeli by coloration (Fig. 8 ; Hamilton et al. 2016: figs 30, 45). Males of A. chiricahua are similar in appearance to A. vorhiesi due to their shared coloration (i. e., general black body with bright orange or red setae on the abdomen, Fig. 8 d ; Hamilton et al. 2016: fig. 142), but possess a larger A 3 / M 4 ratio (0.643 –0.697 vs 0.469 –0.566), and breed later in the fall (October – December vs July – October) (note: males of A. vorhiesi found in October are generally worn and faded whereas males of A. chiricahua are lively and vibrant). Males of A. chiricahua can be further distinguished from other members of the Marxi species group by the following important ratios: A 3 / M 4 (0.643 –0.697) is larger than A. bacadehuachi (0.495), A. catalina (0.477 –0.520), A. madera (0.540 –0.602), and A. peloncillo (0.457 –0.581); and F 1 / T 1 (1.118 –1.196) is slightly smaller than A. marxi (1.199 –1.297). Additional ratios that might be useful for separating males of A. chiricahua from various other members of the Marxi species group include Cl / A 3, Cl / M 3, F 3 / M 4, PTl / M 3, PTl / M 4, PTl / w, and T 1 / F 3 (see Suppl. material 5).

Females of A. chiricahua are similar in appearance to A. vorhiesi due to their overlapping body sizes (Cl 14.230 –15.530 v. 11.230 –16.380) but possess slightly different coloration (Fig. 8 a – c ; Hamilton et al. 2016: fig. 142) and a larger T 1 / P 4 ratio (2.217 –2.311 vs 1.774 –2.091). Furthermore, females of A. chiricahua can be distinguished from other members of the Marxi species group by the following important ratio: T 1 / P 4 (2.217 –2.311) is larger than A. bacadehuachi (0.781), A. catalina (1.985 –2.045), A. madera (1.854 –2.097), A. marxi (1.909 –2.108), and A. peloncillo (1.704 –2.013). Additional ratios that might be useful for separating females of A. chiricahua from various other members of the Marxi species group include SC 4 and M 1 / M 4 (see Suppl. material 5).

Redescription of male holotype

( APH- 3191 Hamilton et al. 2016: figs 36, 37). Specimen collected alive wandering on road, preserved in 80 % ethanol; original coloration faded due to preservation ( Hamilton et al. 2016: fig. 37 a). Left legs I, III, IV, and left pedipalp removed for measurements and photographs; stored in vial with specimen. Right legs III and IV removed for DNA and stored at - 80 ° C at UIM. General coloration: black or faded black. Cephalothorax: Cl 11.420, Cw 11.220; densely clothed with black / faded black pubescence, slightly appressed to surface and longer than lower elevation species, slight iridescence; fringe covered in long setae not closely appressed to surface; foveal groove medium deep and straight; pars cephalica region rises gradually from foveal groove, gently arching anteriorly toward ocular area; AER slightly procurved, PER very slightly recurved; normal sized chelicerae; clypeus slightly extends forward on a curve; LBl 1.37, LBw 1.61; sternum hirsute, clothed with medium black, densely packed setae. Abdomen: densely clothed in short black / brown pubescence with numerous longer, paler setae interspersed (generally red or orange in vita, Hamilton et al. 2016: fig. 36), longer with a more hirsute appearance than lower elevation species; dense dorsal patch of black Type I urticating setae ( Cooke et al. 1972); ventral setae same as dorsal. Legs: hirsute; densely clothed with medium length black / brown setae, and longer setae ventrally. Metatarsus I slightly curved. F 1 12.72; F 1 w 3.28; P 1 4.95; T 1 11.37; M 1 7.61; A 1 6.16; L 1 length 42.812; F 3 9.53; F 3 w 2.98; P 3 4.11; T 3 7.60; M 3 7.79; A 3 6.84; L 3 length 35.878; F 4 11.41; F 4 w 3.20; P 4 4.41; T 4 9.67; M 4 10.28; A 4 7.78; L 4 length 43.559; femur III is normal, not noticeably swollen or wider than other legs ( Hamilton et al. 2016: fig. 37 c). All tarsi fully scopulate. Extent of metatarsal scopulation: leg III (SC 3) = 65.5 %, leg IV (SC 4) = 37.9 % ( Hamilton et al. 2016: fig. 37 d, e). Three ventral spinose setae (megaspines), one retrolateral spinose seta, and five ventral spinose setae at the apical edge on metatarsus III; nine ventral spinose setae (megaspines), one prolateral spinose setae, and three ventral spinose setae at the apical edge on metatarsus IV; two ventral megaspines are present on mating clasper (tibia I); three megaspines, that project anteriorly, can be found on the ventral tibial apophysis ( Hamilton et al. 2016: fig. 37 i). Coxa I: prolateral surface a mix of fine hair-like and thin / very thin tapered setae ( Hamilton et al. 2016: fig. 37 b). Pedipalps: hirsute; densely clothed in the same setal color as the other legs, with numerous longer ventral setae; one spinose seta at the apical, prolateral femur and four spinose setae on the prolateral tibia ( Hamilton et al. 2016: fig. 37 f); PTl 7.34, PTw 2.82. When extended, embolus tapers with a gentle curve to the retrolateral side near apex, embolus slender, no keels ( Hamilton et al. 2016: fig. 37 g, h).

Male variation (n = 6). Cl 7.673 –12.230 (9.864 ± 2.00), Cw 6.968 –11.620 (9.295 ± 0.87), LBl 0.886 –1.368 (1.147 ± 0.08), LBw 1.609 –2.019 (1.773 ± 0.07), F 1 8.560 –13.229 (10.767 ± 0.86), F 1 w 1.892 –3.281 (2.465 ± 0.22), P 1 3.180 –4.947 (3.965 ± 0.31), T 1 7.529 –11.372 (9.396 ± 0.72), M 1 4.452 –7.911 (6.307 ± 0.61), A 1 3.911 –6.605 (5.279 ± 0.49), L 1 length 27.681 –43.106 (35.713 ± 2.96), F 3 6.325 –9.882 (8.167 ± 0.70), F 3 w 1.673 –3.038 (2.499 ± 0.25), P 3 2.397 –4.112 (3.180 ± 0.29), T 3 4.605 –7.673 (6.275 ± 0.55), M 3 4.603 –7.919 (6.414 ± 0.62), A 3 4.452 –6.952 (5.702 ± 0.49), L 3 length 22.517 –35.878 (29.738 ± 2.61), F 4 7.650 –12.048 (9.817 ± 0.83), F 4 w 1.638 –3.205 (2.348 ± 0.24), P 4 2.593 –4.414 (3.368 ± 0.29), T 4 6.314 –10.272 (8.129 ± 0.66), M 4 6.384 –10.378 (8.616 ± 0.76), A 4 4.967 –7.880 (6.415 ± 0.51), L 4 length 28.192 –43.726 (36.345 ± 2.98), PTl 4.885 –7.529 (6.375 ± 0.50), PTw 1.933 –3.171 (2.536 ± 0.20), SC 3 ratio 0.542 –0.656 (0.59 ± 0.02), SC 4 ratio 0.220 –0.416 (0.324 ± 0.03), coxa I setae = fine / very thin and tapered, femur III condition = normal, not noticeably swollen or wider than other legs.

Description of new female exemplar

( APH- 5400: Figs 8 a, b , 9 ). Specimen collected live from burrow, preserved in 80 % ethanol; original coloration faded due to preservation (Fig. 9 a ). Left legs I, III, IV, and pedipalp removed for photographs and measurements; stored in vial with specimen. Genital plate with spermathecae removed and cleared, stored in vial with specimen. General coloration: dark brown and faded black. Cephalothorax: Cl 15.530, Cw 14.350; hirsute, densely clothed with brown / black pubescence closely appressed to surface; fringe densely covered in longer setae; foveal groove medium deep and slightly procurved; pars cephalica region gently rises from thoracic furrow, arching anteriorly toward ocular area; carapace was cracked during specimen measurements; AER slightly procurved, PER recurved; robust chelicerae, clypeus is generally straight but extends forward on a slight curve in front of the eyes; LBl 1.65, LBw 2.69; sternum hirsute, clothed with medium short brown setae. Abdomen: densely clothed dorsally in black / brown setae with numerous longer, paler setae interspersed (generally red or orange in vita, Fig. 8 a, b ); dense dorsal patch of black Type I urticating setae ( Cooke et al. 1972); ventral setae shorter than dorsal. Spermathecae (Fig. 9 f ): paired and separated, tapering from wide bases (not fused) and slightly curving medially towards capitate bulbs. Legs: hirsute; densely clothed in short and medium black / brown pubescence; F 1 12.486, F 1 w 4.127, P 1 5.202, T 1 9.772, M 1 6.865, A 1 6.037, L 1 length 40.362, F 3 10.323, F 3 w 3.768, P 3 4.409, T 3 6.94, M 3 6.828, A 3 7.108, L 3 length 35.608, F 4 11.915, F 4 w 3.634, P 4 4.228, T 4 9.58, M 4 9.569, A 4 6.976, L 4 length 42.268. All tarsi fully scopulate. Extent of metatarsal scopulation: leg III (SC 3) = 41.6 %, leg IV (SC 4) = 43.3 % (Fig. 9 c, d ). Three ventral spinose setae (megaspines), one retrolateral spinose seta, and two ventral spinose setae at the apical edge on metatarsus III; four ventral spinose setae (megaspines), one prolateral spinose setae, and three ventral spinose setae at the apical edge on metatarsus IV. Coxa I: prolateral surface a mix of fine hair-like and thin tapered setae (Fig. 9 b ). Pedipalps (Fig. 9 e ): densely clothed in the same setal color as the other legs; one megaspine at the apical edge of the prolateral femur, five prolateral megaspines on the tibia (two on the apical edge), one ventral megaspine on the tibia.

Female variation (n = 2). Cl 14.230 –15.530 (14.880 ± 0.65), Cw 12.960 –14.350 (13.655 ± 0.69), LBl 1.62–1.65 (1.635 ± 0.01), LBw 2.690 –2.874 (2.782 ± 0.09), F 1 11.362 –12.486 (11.924 ± 0.56), F 1 w 4.058 –4.127 (4.093 ± 0.03), P 1 5.121 –5.202 (5.162 ± 0.04), T 1 9.599 –9.772 (9.686 ± 0.09), M 1 6.151 –6.865 (6.508 ± 0.36), A 1 5.838 –6.037 (5.938 ± 0.10), L 1 length 38.071 –40.362 (39.217 ± 1.15), F 3 8.980 –10.323 (9.652 ± 0.67), F 3 w 3.190 –3.768 (3.479 ± 0.29), P 3 3.737 –4.409 (4.073 ± 0.34), T 3 6.319 –6.940 (6.630 ± 0.31), M 3 6.761 –6.828 (6.795 ± 0.03), A 3 5.657 –7.108 (6.383 ± 0.73), L 3 length 31.454 –35.608 (33.531 ± 2.08), F 4 11.749 –11.915 (11.832 ± 0.08), F 4 w 3.418 –3.634 (3.526 ± 0.11), P 4 4.228 –4.329 (4.279 ± 0.05), T 4 9.439 –9.580 (9.510 ± 0.07), M 4 9.162 –9.569 (9.366 ± 0.20), A 4 6.697 –6.976 (6.837 ± 0.14), L 4 length 41.376 –42.268 (41.822 ± 0.45), SC 3 ratio 0.417 –0.524 (0.47 ± 0.05), SC 4 ratio 0.408 –0.434 (0.421 ± 0.01), coxa I setae = fine / thin and tapered. Spermathecae variation as in Fig. 9 f , Suppl. material 7.

Other material.

United States – Arizona • Cochise County • 1 imm.; Chiricahua Mountains, along Forest Road 42 ; 31.89129 ° N, 109.21079 ° W 1; 1693 m; 26 Oct. 2019; Brent E. Hendrixson, Chris A. Hamilton, Michael A. Jacobi, Chad Campbell & Tom Patterson leg.; UIM; APH-4021 • 1 ♂; Chiricahua Mountains, along Forest Road 42 ; 31.88151 ° N, 109.18972 ° W 1; 1608 m; 27 Oct. 2019; Wyatt Mendez leg.; UIM; APH-4023 • 1 ♂; Chiricahua Mountains, Cave Creek Canyon , along Forest Road 42 ; 31.90136 ° N, 109.15945 ° W 1; 1501 m; 31 Oct. 2018; Brent E. Hendrixson & Michael A. Jacobi leg.; UIM; APH-5004 • 1 ♂; Chiricahua Mountains, Cave Creek Canyon , along Forest Road 42 ; 31.90152 ° N, 109.15932 ° W 1; 1501 m; 11 Oct. 2018; Michael A. Jacobi leg., UIM; APH-5005 • 1 ♂; Chiricahua Mountains, 1 km from entrance to Chiricahua National Monument ; 32.00918 ° N, 109.38123 ° W 1; 1574 m; 30 Oct. 2018; Brent E. Hendrixson & Michael A. Jacobi leg.; UIM; APH-5006 • 1 imm.; Chiricahua Mountains, Cave Creek Visitor Information Center restroom ; 31.89902 ° N, 109.16243 ° W 1; 1512 m; 17 Oct. 2018; Michael A. Jacobi leg.; UIM; APH-5010 • 1 ♂; Chiricahua Mountains, Cave Creek Canyon , along Forest Road 42 at horse corral ; 31.89820 ° N, 109.16286 ° W 1; 1515 m; 16 Nov. 2018; Michael A. Jacobi leg.; AMNH; APH-5049 • 1 ♀; Chiricahua Mountains, on hillside along Forest Road 42 ; 31.89057 ° N, 109.21072 ° W 1; 1720 m; 21 June 2018; Michael A. Jacobi leg.; UIM; APH-5050 • 1 imm.; Chiricahua Mountains, Cave Creek Canyon , Cathedral Vista Point Trail ; 31.88529 ° N, 109.17266 ° W 1; 1567 m; 11 Nov. 2019; Wyatt Mendez & Walter Schoepfle leg.; UIM; APH-5078 • 1 ♂; Chiricahua Mountains, Cave Creek Visitor Information Center ; 31.89916 ° N, 109.16204 ° W 4; 1506 m; 9 Nov. 2021; David Jasper leg.; UIM; APH-5126 • 1 ♂; Chiricahua Mountains, along Forest Road 42 ; 31.88151 ° N, 109.19304 ° W 4; 1618 m; 12 Oct. 2021; Wyatt Mendez leg.; UIM; APH-5144 • 1 ♀; Chiricahua Mountains, Cave Creek Canyon , Cathedral Vista Point area ; 31.88434 ° N, 109.17143 ° W 1; 1634 m; 30 Aug. 2023; Chris A. Hamilton, Leonardo Chávez & Wyatt Mendez leg.; UIM; APH-5400 .

Distribution and natural history.

Aphonopelma chiricahua is endemic to the Chiricahua Mountains (Figs 10 , 11 ) in southeastern Arizona where it has been encountered in mid-elevation Madrean evergreen oak woodlands and pine-oak woodlands (Fig. 10 a – c ; ~ 1500–1720 m). Hamilton et al. (2016) noted that very little was known about the natural history of A. chiricahua . At the time, we had never observed this species in the field despite having spent hundreds of person-hours searching for it during the preceding decade. The lack of observations prompted us to hypothesize that “ these spiders probably seek refuge under rocks and rarely place silk around their burrow entrances ” ( Hamilton et al. 2016: 95, 97). We now know that this is not entirely the case. The burrows of two mature females, one found in June 2018 ( APH- 5050) as reported by Jacobi (2018) and the other found in August 2023 ( APH- 5400; Fig. 10 d ), were indeed covered by a dense mat of silk. Both burrows were found in exposed grassy areas among scattered woodland vegetation. Nevertheless, mature females remain incredibly difficult to find. We are unsure whether this is because females are rare, if they are simply exceptionally good at concealing their burrow entrances, or both. Immature specimens have been found under rocks ( APH- 4021), inside small burrows located along vertical banks ( APH- 5078), and inside human-made structures ( APH- 5010). Mature males are diurnally active in October, November, and perhaps early December (see https://www.facebook.com/watch/?v=785835144804065 for an observation tentatively attributed to this species that was shared by the staff at Chiricahua National Monument).

Figures

Figure 1. Maximum likelihood phylogeny of the Marxi species group based on the mitochondrial gene cytochrome oxidase c subunit I (COX 1). The red clades highlight the diphyly of Aphonopelma jacobii sp. nov. Bootstrap node support values are indicated along branches of interest (*** indicates branches supported with values ≥ 95).

Figure 2. Maximum likelihood phylogeny of the Marxi species group based on Ultraconserved Element phylogenomics (UCE). The red clade highlights the monophyly / exclusivity of Aphonopelma jacobii sp. nov. Except where noted, all nodes are supported by bootstrap support values ≥ 95. All samples included in this tree, except A. jacobii sp. nov. and A. bacadehuachi, are the same samples used in the phylogeny from the US Aphonopelma revision (Hamilton et al. 2016).

Figure 8. Live habitus of Aphonopelma chiricahua a, b in situ female (APH- 5400) c female (APH- 5050) d male (APH- 5144). Photographs of images a and b provided by Leonardo Chávez; photograph of image c provided by Michael A. Jacobi.

Figure 9. Morphology of Aphonopelma chiricahua (female, APH- 5400) a carapace, dorsal view b coxa of leg I, prolateral view c metatarsus and tarsus of leg III, ventral view d metatarsus and tarsus of leg IV, ventral view e pedipalp, prolateral view f spermathecae. Scale bars: 2 mm.

Figure 10. Habitat images of Aphonopelma chiricahua from the Chiricahua Mountains, Cochise County, Arizona a, b Madrean pine-oak woodland near the Cathedral Vista Trail off Forest Road 42 c rocky and grassy microhabitat near the Cathedral Vista Trail d silk-covered burrow of a mature female (APH- 5400). Photographs of images b and d provided by Leonardo Chávez.

Figure 11. Map showing the known distribution of Aphonopelma jacobii sp. nov. (red circles) and A. chiricahua (yellow circles) in the Chiricahua Mountains, Cochise County, Arizona.