Difference between revisions of "Aptostichus cahuilla"

Latest revision as of 09:53, 20 December 2012

Taxonavigation

Ordo: Araneae
Familia: Euctenizidae
Genus: Aptostichus

Name

Aptostichus cahuilla Bond, 2012 sp. n. – Wikispecies link – Winchester Trapdoor Spider’ ZooBank link – Pensoft Profile

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, -117.0922051, 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, -117.11571, 444m, J Bond 01.ii.2004 [MY2521, 1juv, AUMNH]; Winchester, 33.7138, -117.09151, 470m, W Icenogle 18.i.1970 [AP245, 1♂, AMNH]; Winchester, 1.6km NW of town center, vicinity of Double Butte, 33.7138, -117.09131, 466m, J Bond, W Icenogle 25.iii.1996 [AP737, 1♀, AUMNH]; Winchester, 1.6km NW of town center, vicinity of Double Butte, 33.7148, -117.09221, 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, -117.32513, 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, -117.5973, 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.

Original Description

• Bond, J; 2012: Phylogenetic treatment and taxonomic revision of the trapdoor spider genus Aptostichus Simon (Araneae, Mygalomorphae, Euctenizidae) ZooKeys, 252: 1-209. doi

Images

Figures 17–20. Box plots for quantitative measurements used in phylogenetic analysis and species diagnosis; ratios are given in values multiplied by 100 (y-axis); characters states are indicated above and below horizontal line bisecting graph; species abbreviations (x-axis) defined in Table 1. 17 sternum length to width 18 labium length to width 19 leg IV tarsus length to femur length 20 leg I tibia length to femur length.  Figures 21–24. Box plots for quantitative measurements used in phylogenetic analysis and species diagnosis; ratios are given in values multiplied by 100 (y-axis); characters states are indicated above and below horizontal line bisecting graph; species abbreviations (x-axis) defined in Table 1. 21 leg I metatarsus length to femur length 22 leg I tarsus length to femur length 23 male palpal tibia width to length 24 palpal tibia length to carapace length.  Figures 204–209. Aptostichus cahuilla sp. n. 204–207 male holotype from Riverside County, Winchester (AP392); scale bars = 1.0mm 204 habitus [805952] 205 retrolateral aspect, leg I [805944] 206 prolateral aspect, leg I [805948] 207 retrolateral aspect, pedipalp [805950] 208 line drawings of male leg I tibia and metatarsus spination pattern variation 209 cleared spermathecae, female paratype (AP221) [806626]; scale bar = 0.1mm.  Maps 23, 24. Aptostichus cahuilla Bond sp. n. 23 distribution of known specimens 24 predicted distribution; cooler colors–blue shades–represent areas of high probability of occurrence, warmer colors–yellow and orange shades–represent areas of low probability of occurrence.