Aphonopelma jacobii Hamilton & Hendrixson & Silvestre Bringas 2024, sp. nov.
Creators: name: Hamilton, Chris A.
name: Hendrixson, Brent E.
name: Silvestre Bringas, Karina
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Theraphosidae
Aphonopelma
Aphonopelma jacobii

description: Aphonopelma jacobii Hamilton & Hendrixson, 2024 sp. nov.
Figs 3, 4, 5, 6, 7, 11
Aphonopelma chiricahua, in part: Hamilton et al. 2016: 90, 91, 93–95, fig. 38 (APH- 2097, misidentification); 95 (APH- 2101, APH- 2102, APH- 2105, APH- 2480 - A, APH- 2480 - B, APH- 2548, misidentifications).
Type material.
Holotype. United States • ♂; Arizona, Cochise County, Chiricahua Mountains, along Forest Road 42 D above Onion Saddle; 31.92838 ° N, 109.26311 ° W 1; 2364 m; 31 Oct. 2018; Brent E. Hendrixson & Michael A. Jacobi leg.; UIM; APH-5002.
Paratype. United States • 1 ♀; same data as for holotype; UIM; APH-5001 • 1 ♂; same data as for holotype; AMNH; APH-5003.
Etymology.
The specific epithet is a patronym in honor of our friend, Michael A. Jacobi, who facilitated many of our field trips into the Chiricahua Mountains in 2018 and 2019. In addition, he generously carried out field work in the MSI on our behalf and discovered many important specimens, including the first female burrows of A. chiricahua and this remarkable new species. His tireless work in the field and passion for natural history have immensely helped improve our knowledge of tarantula biology and biodiversity in the Chiricahua Mountains and surrounding areas.
Diagnosis.
Aphonopelma jacobii sp. nov. 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. Nuclear DNA identifies A. jacobii sp. nov. as a monophyletic lineage (Fig. 2) that is sister to A. marxi (distributed along the Colorado Plateau) and phylogenetically distinct from the other tarantula species endemic to the Chiricahua Mountains (i. e., A. chiricahua). Aphonopelma jacobii sp. nov. is probably the only tarantula species encountered in the high-elevation mixed conifer forests of the Chiricahua Mountains, but its distribution overlaps with A. chalcodes Chamberlin, 1940, A. chiricahua, A. gabeli Smith, 1995, and A. vorhiesi at lower elevations in the oak and pine-oak woodlands.
Aphonopelma jacobii sp. nov. is readily distinguished from adult A. chalcodes and A. gabeli by coloration and size (Fig. 3; Hamilton et al. 2016: figs 30, 45). Males of the new species 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. 3 a; Hamilton et al. 2016: fig. 142), but are noticeably smaller (Cl 6.708 –8.955 vs 10.018 –13.980), possess a larger A 3 / M 4 ratio (0.659 –0.790 vs 0.469 –0.566), and breed later in the fall (October – November vs July – October) (note: males of A. vorhiesi found in October are generally worn and faded whereas males of A. jacobii sp. nov. are lively and vibrant). Males of A. jacobii sp. nov. and A. chiricahua are very similar morphologically and behaviorally. They possess similar coloration (Figs 3 a, 8 d) and share a common breeding period, but the new species does separate slightly from A. chiricahua in PCA morphospace (S 4 A), is statistically smaller (Cl 7.679 ± 0.71 vs 9.864 ± 2.00, t (18) = 3.6964, P = 0.0017), possesses a slightly smaller T 1 / P 4 ratio (2.175 –2.545 vs 2.576 –2.991), and has a proportionally shorter embolus relative to the palpal bulb (Fig. 4 g, h; Hamilton et al. 2016: fig. 37 g, h). Males of A. jacobii sp. nov. can be further distinguished from other members of the Marxi species group by the following important ratios and measurements: T 1 / P 4 (2.175 –2.545) is smaller than A. catalina (2.814 –3.033); A 3 / M 4 (0.659 –0.790) 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 Bl _ r (2.505 –3.061) is smaller than A. marxi (3.194 –3.781). Additional ratios that might be useful for separating males of A. jacobii sp. nov. from various other members of the Marxi species group include Cl / A 3, Cl / M 3, PTl / M 3, PTl / M 4, and T 1 / F 3 (see Suppl. material 5).
Females of A. jacobii sp. nov. are noticeably smaller than A. chiricahua and A. vorhiesi (Cl 7.621 –9.018 v. 14.230 –15.530 and 11.230 –16.380, respectively), separate in PCA morphospace (S 4 B), and possess slightly different coloration (Figs 3 b, 8 a – c; Hamilton et al. 2016: fig. 142). Furthermore, females of the new species can be distinguished from other members of the Marxi species group by the following important ratio: M 3 / F 4 (0.509 –0.534) is smaller than A. bacadehuachi (0.613), A. catalina (0.582 –0.604), A. madera (0.550 –0.616), A. marxi (0.550 –0.598), A. peloncillo (0.598 –0.655), and A. vorhie s i (0.587 –0.657). Additional ratios that might be useful for separating females of A. jacobii sp. nov. from various other members of the Marxi species group include F 1 / T 4, M 1 / A 3, SC 4, and T 1 / T 4 (see Suppl. material 5).
Description of male holotype
(APH- 5002: Figs 3 a, 4). Specimen collected alive wandering on road, preserved in 80 % ethanol; original coloration faded due to preservation (Fig. 3 a). Left legs I, III, IV, and left pedipalp removed for measurements and photographs; stored in vial with specimen. Right leg III removed for DNA and stored at - 80 ° C at UIM. General coloration: black or faded black. Cephalothorax: Cl 6.708, Cw 6.509; 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 area; AER procurved, PER slightly recurved; normal sized chelicerae; clypeus generally straight but extends forward on a slight curve near the eyes; LBl 0.942, LBw 1.596; sternum hirsute, clothed with short black / brown, densely packed setae. Abdomen: densely clothed in short black / brown pubescence with numerous longer, paler setae interspersed (generally red or orange in vita, Fig. 3 a); dense dorsal patch of black Type I urticating setae (Cooke et al. 1972); ventral setae same as dorsal. Legs: Hirsute; densely clothed with short, similar length black / brown setae, and longer setae dorsally. Metatarsus I slightly curved. F 1 7.478; F 1 w 1.836; P 1 2.780; T 1 6.482; M 1 4.543; A 1 4.251; L 1 length 25.534; F 3 5.765; F 3 w 1.823; P 3 2.438; T 3 4.445; M 3 4.559; A 3 4.475; L 3 length 21.682; F 4 7.082; F 4 w 1.554; P 4 2.573; T 4 6.199; M 4 6.068; A 4 4.980; L 4 length 26.902; femur III is normal, not noticeably swollen or wider than other legs (Fig. 4 c). All tarsi fully scopulate. Extent of metatarsal scopulation: leg III (SC 3) = 48.8 %, leg IV (SC 4) = 29.3 % (Fig. 4 d, e). Six ventral spinose setae (megaspines), one prolateral spinose seta, and four ventral spinose setae at the apical edge on metatarsus III; nine ventral spinose setae (megaspines), two prolateral and one retrolateral spinose setae, and eight ventral spinose setae at the apical edge on metatarsus IV; one prolateral megaspine and two ventral megaspines are present on the prolateral tibia of the mating clasper (tibia I); two megaspines, that project anteriorly, can be found at the apex of each tibial apophyses (Fig. 4 i). Coxa I: prolateral surface a mix of fine hair-like and very thin tapered setae (Fig. 4 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 two spinose setae on the prolateral tibia (Fig. 4 f); PTl 4.627, PTw 1.763. When extended, embolus tapers with a gentle curve to the retrolateral side near apex, embolus slender, no keels (Fig. 4 g, h).
Male variation (n = 14). Cl 6.708 –8.955 (7.679 ± 0.71), Cw 6.254 –8.654 (7.467 ± 0.23), LBl 0.684 –1.340 (0.930 ± 0.05), LBw 0.985 –1.971 (1.513 ± 0.09), F 1 7.145 –9.585 (8.220 ± 0.19), F 1 w 1.821 –2.596 (2.124 ± 0.06), P 1 2.780 –3.825 (3.225 ± 0.08), T 1 5.851 –7.851 (6.863 ± 0.54), M 1 4.090 –5.524 (4.807 ± 0.11), A 1 3.572 –4.975 (4.307 ± 0.10), L 1 length 23.568 –31.239 (27.422 ± 0.59), F 3 5.591 –7.285 (6.396 ± 0.14), F 3 w 1.688 –2.478 (2.012 ± 0.06), P 3 2.304 –3.177 (2.620 ± 0.07), T 3 4.162 –5.726 (4.812 ± 0.12), M 3 4.379 –5.807 (4.916 ± 0.11), A 3 3.955 –5.389 (4.724 ± 0.09), L 3 length 20.391 –27.358 (23.468 ± 0.50), F 4 6.648 –9.006 (7.728 ± 0.18), F 4 w 1.554 –2.349 (1.90 ± 0.06), P 4 2.524 –3.516 (2.861 ± 0.08), T 4 5.784 –7.380 (6.647 ± 0.13), M 4 5.772 –8.177 (6.762 ± 0.16), A 4 4.944 –6.379 (5.464 ± 0.11), L 4 length 25.672 –34.458 (29.463 ± 0.62), PTl 4.420 –5.822 (5.113 ± 0.11), PTw 1.763 –2.419 (2.041 ± 0.05), SC 3 ratio 0.414 –0.609 (0.533 ± 0.01), SC 4 ratio 0.283 –0.404 (0.351 ± 0.01), coxa I setae = fine / very thin and tapered, femur III condition = normal, not noticeably swollen or wider than other legs.
Description of female paratype
(APH- 5001: Figs 3 b, 5). Specimen collected alive from burrow, preserved in 80 % ethanol; original coloration faded due to preservation (Fig. 5 a). Left legs I, III, IV, and pedipalp removed for photographs and measurements; stored in vial with specimen. Right leg III removed for DNA and stored at - 80 ° C at UIM. Genital plate with spermathecae removed and cleared, stored in vial with specimen. General coloration: black or faded black and brown. Cephalothorax: Cl 9.018, Cw 8.908; hirsute, densely clothed with black / faded 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 towards ocular area; AER procurved, PER slightly recurved; robust chelicerae, clypeus extends forward on a slight curve; LBl 1.403, LBw 2.110; sternum hirsute, clothed with shorter black / faded black setae. Abdomen: densely clothed dorsally in short black setae with numerous longer, paler setae interspersed (generally red or orange in vita, Fig. 3 b); dense dorsal patch of black Type I urticating setae (Cooke et al. 1972); ventral setae same as dorsal. Spermathecae (Fig. 5 f): paired and separated, tapering from wide bases (not fused) and slightly curving medially towards capitate bulbs. Legs: very hirsute, particularly ventrally; densely clothed in short and medium black / brown pubescence, with longer setae colored similarly as the long abdominal setae; F 1 7.661; F 1 w 2.481; P 1 3.568; T 1 5.864; M 1 3.553; A 1 3.854; L 1 length 24.500; F 3 6.206; F 3 w 2.032; P 3 2.628; T 3 4.230; M 3 4.191; A 3 4.340; L 3 length 21.595; F 4 7.885; F 4 w 2.122; P 4 2.969; T 4 6.156; M 4 6.079; A 4 4.845; L 4 length 27.904. All tarsi fully scopulate. Extent of metatarsal scopulation: leg III (SC 3) = 50.4 %, leg IV (SC 4) = 27.3 % (Fig. 5 d). Two ventral spinose setae (megaspines) and six ventral spinose setae at the apical edge on metatarsus III; eight ventral spinose setae (megaspines), one prolateral spinose setae, and six ventral spinose setae at the apical edge on metatarsus IV. Coxa I: prolateral surface a mix of fine hair-like and very thin tapered setae (Fig. 5 b). Pedipalps (Fig. 5 e): Densely clothed in the same setal color as the other legs; two prolateral megaspines (one of these apical) and two apical ventral megaspines are present on the palpal tibia.
Female variation (n = 6). Cl 7.621 –9.018 (8.320 ± 0.44), Cw 7.433 –8.908 (8.171 ± 0.47), LBl 1.261 –1.403 (1.332 ± 0.04), LBw 1.978 –2.110 (2.044 ± 0.04), F 1 6.692 –7.661 (7.177 ± 0.31), F 1 w 2.131 –2.481 (2.306 ± 0.11), P 1 2.885 –3.568 (3.227 ± 0.22), T 1 4.952 –5.864 (5.399 ± 0.32), M 1 3.230 –3.553 (3.392 ± 0.10), A 1 3.530 –3.854 (3.692 ± 0.10), L 1 length 21.659 –24.500 (23.080 ± 0.90), F 3 5.383 –6.206 (5.795 ± 0.26), F 3 w 1.808 –2.032 (1.920 ± 0.07), P 3 2.408 –2.628 (2.518 ± 0.07), T 3 3.847 –4.230 (4.039 ± 0.12), M 3 3.608 –4.191 (3.900 ± 0.18), A 3 4.104 –4.340 (4.222 ± 0.07), L 3 length 19.350 –21.595 (20.473 ± 0.71), F 4 6.867 –7.855 (7.361 ± 0.31), F 4 w 1.968 –2.122 (2.045 ± 0.05), P 4 2.596 –2.969 (2.783 ± 0.12), T 4 5.630 –6.156 (5.893 ± 0.17), M 4 5.309 –6.079 (5.694 ± 0.24), A 4 4.741 –4.845 (4.793 ± 0.03), L 4 length 25.143 –27.904 (26.524 ± 0.87), SC 3 ratio 0.505 –0.571 (0.538 ± 0.02), SC 4 ratio 0.273 –0.275 (0.274 ± 0.01), coxa I setae = fine / very thin and tapered. Spermathecae variation as in Fig. 5 f, Suppl. material 6 (and Hamilton et al. 2016: fig. 38 for APH- 2097).
Other material.
United States – Arizona • Cochise County • 1 ♀; Chiricahua Mountains, Southwest Research Station; 30 Nov. 1965; Jon Jenson leg.; AMNH; APH-2097 • 1 ♂; Chiricahua Mountains, Cave Creek Canyon; 30 Nov. 1963; V. Roth leg.; AMNH; APH-2101 • 1 ♂; Chiricahua Mountains, Upper Cave Creek Canyon; 1966; Marlene Posedly leg.; AMNH; APH-2102 • 1 ♂; Chiricahua Mountains, Southwest Research Station; 31 Oct. 1956; E. Ordway leg.; AMNH; APH-2105 • 1 ♂; Chiricahua Mountains, Sunny Flat; 30 Oct. 1971; V. Roth leg.; AMNH; APH-2480-A • 1 ♂; Chiricahua Mountains, Southwest Research Station; 20 Nov. 1971; V. Roth leg.; AMNH; APH-2480-B • 1 ♂; Chiricahua Mountains, Rustler and Long Park; 4 Nov. 1970; Joan Harper leg.; AMNH; APH-2548 • 1 imm.; Chiricahua Mountains, Barfoot Park Helispot; 31.91516 ° N, 109.28504 ° W 1; 2493 m; 27 Oct. 2019; Tom Patterson, Brent E. Hendrixson, Chris A. Hamilton, Michael A. Jacobi, Chad Campbell & Wyatt Mendez leg.; UIM; APH-4005 • 1 imm.; Chiricahua Mountains, along Forest Road 42 D above Onion Saddle; 31.92838 ° N, 109.26311 ° W 1; 2364 m; 20 Oct. 2019; Wyatt Mendez leg.; UIM; APH-4024 • 1 ♀; Chiricahua Mountains, on hillside along Forest Road 42 A; 31.88062 ° N, 109.22087 ° W 1; 1717 m; 27 Oct. 2019; Chris A. Hamilton, Brent E. Hendrixson, Michael A. Jacobi, Wyatt Mendez, Chad Campbell & Tom Patterson leg.; UIM; APH-4006 • 2 ♀; Chiricahua Mountains, Barfoot Park Helispot; 31.91516 ° N, 109.28504 ° W 1; 2493 m; 27 Oct. 2019; Wyatt Mendez, Brent E. Hendrixson, Chris A. Hamilton, Michael A. Jacobi, Chad Campbell & Tom Patterson leg.; UIM; APH-4018; AMNH; APH-4019 • 1 ♂; Chiricahua Mountains, along Forest Road 42; 31.88139 ° N, 109.18732 ° W 1; 1593 m; 26 Oct. 2019; Chris A. Hamilton & Brent E. Hendrixson leg.; UIM; APH-4020 • 1 ♂; Chiricahua Mountains, 1 Pogo Hill; 31.88061 ° N, 109.20386 ° W 1; 1662 m; 27 Oct. 2019; Chris A. Hamilton, Brent E. Hendrixson & Wyatt Mendez leg.; UIM; APH-4022 • 1 ♂; Chiricahua Mountains, Barfoot Park Helispot; 31.91516 ° N, 109.28504 ° W 1; 2493 m; 26 Oct. 2019; Chad Campbell, Michael A. Jacobi & Tom Patterson leg.; UIM; APH-4029 • 1 ♀; Chiricahua Mountains, 1 Pogo Hill; 31.88061 ° N, 109.20386 ° W 1; 1662 m; 9 Sept. 2019; Wyatt Mendez leg.; UIM; APH-5079 • 2 ♂; Chiricahua Mountains, Barfoot Park Helispot; 31.91516 ° N, 109.28504 ° W 1; 2493 m; 3 Nov. 2019; Wyatt Mendez leg.; UIM; APH-5080, APH-5081 • 1 ♂; Chiricahua Mountains, along Forest Road 42 D above Onion Saddle; 31.92838 ° N, 109.26311 ° W 1; 2364 m; 8 Nov. 2019, Wyatt Mendez leg.; UIM; APH-5082.
Distribution and natural history.
Aphonopelma jacobii sp. nov. is endemic to the Chiricahua Mountains (Figs 7, 11) in southeastern Arizona where it has been encountered in plant communities ranging from mid-elevation Madrean evergreen oak woodlands in Cave Creek Canyon (Fig. 7 e) to high-elevation mixed conifer forests near Onion Saddle (Fig. 7 a, b) and Barfoot Park (Fig. 7 c, d). To our knowledge, it is the only tarantula in the Chiricahua Mountains encountered above the pine-oak woodland zone. The highest confirmed elevation record for this species — as observed by us — is just below 2500 m at Barfoot Park, but other sightings suggest it is found perhaps as high as 2700 m near Rustler and Long Parks (see APH- 2548, misidentified as A. chiricahua in Hamilton et al. 2016). In the United States, only A. marxi has been reported from higher elevations (~ 2830 m in the Chuska Mountains of northeastern New Mexico, APH- 0452 in Hamilton et al. 2016), but still far below the elevation records for the remarkable neotropical tarantula genera Antikuna Kaderka, Ferretti, West, Lüddecke & Hüsser, 2021 (4689 m, Kaderka et al. 2021), Hapalotremus Simon, 1903 (4524 m, Ferretti et al. 2018), Bistriopelma Kaderka, 2015 (4398 m, Kaderka 2015), and Euathlus Ausserer, 1875 (4153 m, Quispe-Colca and Ferretti 2021) from the South American Andes.
Mature female and immature individuals of A. jacobii sp. nov. have only been extracted from burrows (i. e., specimens have not been observed beneath rocks or other surface debris). Burrows are generally located in meadows or exposed patches of soil with limited overstory structure. This perhaps allows their burrows to receive more direct sunlight to maintain higher temperatures in these otherwise cool habitats. Burrow entrances of mature females measure c. 15 mm in diameter and have been observed with (Fig. 7 f) and without traces of silk along the perimeter. The breeding period for this species appears to be limited. Mature males are active during October and November, similar to other fall-breeding members of the Marxi species group in southeastern Arizona, including A. chiricahua (Hendrixson et al. 2015; Hamilton et al. 2016). In fact, males of A. jacobii sp. nov. and A. chiricahua (APH- 4020 and APH- 4023, respectively) were observed within 250 m of each other on consecutive days in late October 2019. Males are most frequently encountered during daylight hours, but one individual (APH- 4022) was observed wandering on a mild evening (c. 20 ° C) during early twilight. Two other males (APH- 5002, APH- 5003) were observed at the type locality on a breezy and cool morning (~ 5–10 ° C, ~ 1030 hrs).
The discovery of A. jacobii sp. nov. documents the first known case of syntopy between five species of Aphonopelma (i. e., the distributions of A. jacobii sp. nov., A. chalcodes, A. chiricahua, A. gabeli, and A. vorhiesi overlap in Cave Creek Canyon). As noted above, the breeding periods of A. jacobii sp. nov. and A. chiricahua — but not A. chalcodes, A. gabeli, or A. vorhiesi — coincide with each other. It is unknown how these two species maintain cohesion and reproductive isolation in the face of significant overlap between their distributions and breeding periods. Future studies should investigate the various factors that promote selection for prezygotic or postzygotic reproductive barriers and reduce potential hybridization between these synchronously breeding populations (see also Prentice 1997).
description: Published as part of 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, pp. 61-98 in ZooKeys 1210 on pages 61-98, DOI: 10.3897/zookeys.1210.125318