Aptostichus cahuilla, Bond, Jason E., 2012

Bond, Jason E., 2012, Phylogenetic treatment and taxonomic revision of the trapdoor spider genus Aptostichus Simon (Araneae, Mygalomorphae, Euctenizidae), ZooKeys 252, pp. 1-209 : 101-106

Aptostichus cahuilla sp. n. Figures 204-209Map 23, 24

Types.

Male holotype (AP392) and female paratype (AP221) from California, Riverside County, Winchester, 1.6km NW of town center, vicinity of Double Butte, 33.714924, -117.092205 1, 478m, coll. W. Icenogle 3.ix.1967 & 15.x.1967, deposited in AUMNH.

Etymology.

The specific epithet is a noun in apposition taken from the Cahuilla Native American Tribal Group, which once resided in Southern California.

Diagnosis.

Males (Fig. 204) can be diagnosed on the basis of a unique conformation of the distal - most spination pattern of tibia I which consists of 5-9 short spines that are always overlapping (Figs 205, 208). This spination pattern is most similar to Aptostichus derhamgiulianii , however the retrolateral cymbium surface of Aptostichus derhamgiulianii bears a number of small, distinct spines, whereas that of Aptostichus cahuilla does not. Additionally, the MA4/MF4 ratio (Fig. 19) of Aptostichus derhamgiulianii is greater than that of Aptostichus cahuilla (i.e., the overall length of tarsus IV is greater for Aptostichus derhamgiulianii ). Females can be distinguished from those of other known sympatric species of Aptostichus ( Aptostichus icenoglei , Aptostichus hesperus , and Aptostichus atomarius ) simply by their small size (Cl <4.6). Additional features that distinguish females of this species from others that are closely related ( Aptostichus hesperus and Aptostichus aguacaliente ) is the presence of smaller sigilla that tend to be more widely spaced. Males can be further diagnosed on the basis of a greater PTw/PTl ratio (Fig. 23).

Description of male holotype.

Specimen preparation and condition. Specimen collected live from pitfall trap, preserved in 80% EtOH. Coloration moderately faded. Pedipalp, leg I left side removed, stored in vial with specimen. General coloration. Carapace, chelicerae, legs strong brown 7.5YR 4/6; dusky purple markings along anterior margins of carapace. Abdomen uniform yellowish brown 10YR 5/4 dorsally, ventrum, spinnerets pale yellow; mottled chevron pattern (Fig. 204). Cephalothorax. Carapace 3.88 long, 3.28 wide, lightly hirsute, stout black bristles along fringe; surface smooth, pars cephalica elevated. Fringe, posterior margin with black bristles. Foveal groove deep, straight. Eyes on mound. AER slightly procurved, PER slightly recurved. PME slightly larger in diameter than AME. Sternum moderately setose, STRl 2.00, STRw 1.84. Posterior sternal sigilla small, positioned laterally, anterior sigilla pairs small, oval, marginal. Chelicerae with distinct anterior tooth row comprising 5 teeth, posterior margin with single row of small denticles. Palpal endites with patch of small cuspules on proximal, inner margin, labium with few cuspules, LBw 0.68, LBl 0.43. Rastellum consists of 5 very stout spines, one spine separated laterally. Abdomen. Setose, heavy black setae intermingled with fine black setae. Legs. Leg I: 3.76, 2.60, 2.29, 1.55, 1.30; leg IV: 3.52, 1.70. Light tarsal scopulae on legs I, II. Tarsus I with single, slightly staggered row of 10 trichobothria. Leg I spination pattern illustrated in Figures 205, 206, 208; TSp 3, TSr 3, TSrd 5. Pedipalp. Articles stout, lacking distinct spines (Figs 207). PTw 0.80, PTl 1.68, Bl 0.85. Embolus slender, with slight curvature at terminus (Fig. 207).

Variation (9). Cl 3.42-4.38, 3.89 ± 0.09; Cw 2.79-3.63, 3.11 ± 0.08; STRl 1.92-2.46, 2.09 ± 0.05; STRw 1.65-2.13, 1.84 ± 0.05; LBw 0.57-0.69, 0.64 ± 0.01; LBl 0.30-0.44, 0.37 ± 0.02; leg I: 3.18-4.13, 3.60 ± 0.10; 2.16-2.94, 2.52 ± 0.08; 1.92-2.40, 2.20 ± 0.05; 1.32-1.68, 1.55 ± 0.04; 1.14-1.38, 1.27 ± 0.02; leg IV: 3.00-3.75, 3.38 ± 0.09; 1.5-1.81, 1.65 ± 0.04; PTl 1.44-1.79, 1.62 ± 0.04; PTw 0.72-0.81, 0.77 ± 0.01; Bl 0.75-0.90, 0.81 ± 0.02; TSp 3-5, 3.78 ± 0.28; TSr 2-5, 4.11 ± 0.35; TSrd 5-9, 6.22 ± 0.46.

Description of female paratype.

Specimen preparation and condition. Female collected live from burrow, prepared in same manner as male holotype. Genital plate removed, cleared in trypsin, stored in microvial with specimen. General coloration. Carapace, legs, chelicerae, strong brown 7.5YR 4/6. Abdomen uniform dark grayish brown dorsally 10YR 4/2 with mottled striping, ventral, spinnerets pale yellow; more recently collected specimens much darker in color. Cephalothorax. Carapace 4.55 long, 3.64 wide, glabrous; generally smooth surface, pars cephalica moderately elevated. Fringe lacks setae. Foveal groove deep, slightly procurved, straight in most specimens. Eye group slightly elevated on low mound. AER slightly procurved, PER slightly recurved. PME-AME subequal diameter. Sternum widest at coxae II/III, moderately setose, STRl 2.58, STRw 2.15. Three pairs of sternal sigilla anterior pairs small, oval, marginal, posterior pair small, oval-suboval, mid-marginally positioned. Chelicerae anterior tooth row comprising 5 teeth with posterior margin denticle patch comprising 3 rows. Palpal endites with 27 cuspules concentrated at inner (promargin) posterior heel; labium with 6 cuspules, LBw 1.25, LBl 0.41. Rastellum consists of 5 very stout spines not on mound, one spine positioned laterally; fringe of short spines along distal promargin extending upward from rastellum. Abdomen. Moderately setose, appears elongate relative to other species. PLS all 3 segments with spigots. Terminal segment 1/2 length of medial segment, 2 enlarged spigots visible at tip. PMS single segment, with spigots, short with rounded terminus. Legs. Anterior two pairs noticeably more slender than posterior pairs. Leg I 10.08 long. Tarsus I with single staggered row of 12 trichobothria. Legs I, II with moderately heavy scopulae on tarsi, metatarsi; light sparse scopulae on legs III, IV tarsi, PTLs 8, TBs 3. Rudimentary preening comb on retrolateral distal surface at tarsus - metatarsus joint of metatarsus III, IV. Spermathecae. Simple spermathecal bulbs with elongate, heavily sclerotized median stalk neck, sinuous; basal extension comprises a small bulb (Fig. 209).

Variation (4). Cl 3.47-4.55, 3.98 ± 0.22; Cw 2.98-3.8, 3.45 ± 0.18; STRl 2.00-2.58, 2.30 ± 0.12; STRw 1.72-2.15, 1.98 ± 0.1; LBw 0.75-1.25, 0.91 ± 0.12; LBl 0.34-0.51, 0.41 ± 0.04; Leg I: 7.73-10.08, 8.96 ± 0.51; ANTd 5-6, 5.25 ± 0.25; PTLs 8-10, 9.00 ± 1.00; TBs 2-3, 2.50 ± 0.50.

Material examined.

United States: California: Riverside Co.: just S Winchester on Leona Rd, ~1.6km S intersection w/Patton Ave, 33.6771, -117.1157 1, 444m, J Bond 01.ii.2004 [MY2521, 1juv, AUMNH]; Winchester, 33.7138, -117.0915 1, 470m, W Icenogle 18.i.1970 [AP245, 1♂, AMNH]; Winchester, 1.6km NW of town center, vicinity of Double Butte, 33.7138, -117.0913 1, 466m, J Bond, W Icenogle 25.iii.1996 [AP737, 1♀, AUMNH]; Winchester, 1.6km NW of town center, vicinity of Double Butte, 33.7148, -117.0922 1, 476m, J Bond 29.i.1997 [AP1203, 1♀, AUMNH], W Icenogle 23.ii.1973 [AP246, 1♂, AMNH], 05.i.1977 [AP2471♂AMNH], 27.xii.1977 [AP241, 1♂, CAS], 03.ix.1967 [AP392, 1♀, 1♂, CAS], 15.x.1967 [AP221, 1♀, 29juv, AMNH], 20.xi.1967 [AP227, 1♂, AMNH], 04.ii.1968 [AP240, 1♂, AMNH], 17.xi.1972 [AP238, 1♂, AMNH]; University of California, Riverside Campus, 33.9742, -117.3251 3, 327m, W Icenogle 05.x.1967 [AP232, 1♀, 12juv, AMNH], 10.x.1967 [AP222, 1♀, 31juv, CAS], 27.x.1967 [AP239, 1♂, AMNH]; San Bernardino Co.: Alta Loma, 34.122, -117.597 3, 412m, D Bixler 04.iv.1969 [AP337, 1♂, AMNH], 15.iv.1969 [AP338, 1♂, AMNH], 20.iv.1969 [AP336, 1♂, AMNH].

GenBank accession.

16S-tRNAval-12S: JX103293

Distribution and natural history.

Aptostichus cahuilla is known from only from a few localities in Riverside County and one in southwestern San Bernardino County. Experience collecting this species indicates that it is found primarily in chaparral habitat but is considerably less abundant than the species with which it is sympatric (e.g., Aptostichus atomarius , Aptostichus icenoglei , and Aptostichus hesperus ).

Conservation status.

The conservation status of Aptostichus cahuilla is likely to be considered imperiled; it is rare in collections, abundance is very low, and it is relatively restricted in distribution.

Species concept applied.

Morphological/Phylogenetic.