Comprehensive DescriptionRead full entry
Antrodiaetus unicolor (Hentz 1841)
(Figures 1, 3-5, 9-10; Tables 1-2)
Mygale unicolor Hentz 1841: 42; Hentz 1842: 57, pl. 7, fig. 5.
Mygale gracilis Hentz 1841: 42 (synonymized by Coyle 1971: 335); Hentz 1842: 56, pl. 7, fig. 4.
Antrodiaetus unicolor : Ausserer 1871: 136; Roewer 1942: 189; Bonnet 1955: 335; Coyle 1971: 335-344, figs. 113, 120, 130, 138, 145-146, 158, 173-174, 188-194, 234-240, 270-279, 313, 315, 318; Gertsch & Platnick 1979: 4, figs. 5-6; Eskov & Zonstein 1990: 354: figs. 28-29.
Closterochilus gracilis : Ausserer 1871: 142; Roewer 1942: 190.
Eurypelma bicolor : Marx 1883: 24 (incorrect subsequent spelling).
Eurypelma gracilis : Marx 1883: 24.
Brachybothrium accentuatum Simon 1884: 315 (synonymized by Coyle 1971); Roewer 1942: 189; Bonnet 1955: 906.
Nidivalvata marxii Atkinson 1886: 110-111, 113, 116, 130-131, pl. 5, figs. 8-10, 13, 17-18, 23 (synonymized by Coyle 1971).
Nidivalvata angustata Atkinson 1886: 130, 113, 117 (synonymized by Coyle 1971).
Brachybothrium marxi : Simon 1890: 310; Roewer 1942: 190; Bonnet 1955: 906.
Brachybothrium angustatum : Simon 1890: 310; Petrunkevitch 1911: 52; Roewer 1942: 190; Bonnet 1955: 906.
Anthrodiaetus unicolor : Simon 1890: 312.
Brachybothrium unicolor : Comstock 1912: 249.
Brachybothrium pacificum : Barrows 1918: 298 (misidentification); Barrows 1925: 493, pl. 37, figs. 17-22 (misidentification).
Missulena gracilis : Petrunkevitch 1939: 213; Bonnet 1957: 2939.
Antrodiaetus bicolor : Vogel 1962: 246.
Type data. United States : Alabama : Dekalb County : DeSoto State Park near Fort Payne ( 34.50°N , 85.62°W ), July–August 1937 (collector unknown, probably W.B. Jones ), maleneotype (herein designated) ( AMNH ) .
FIGURE 1. Live habitus of adult female Antrodiaetus from Coweeta. A, A. unicolor ( MY 2300); B, A. microunicolornew species ( MY 2422). Note the size difference. Scale bar = 5 mm .
Hentz (1841) described Mygale unicolor on the basis of a female specimen from Alabama. In the same paper, he described a male, also from Alabama, which he named M. gracilis . Unfortunately, both specimens have been destroyed and the exact locality from which these spiders were collected in Alabama is unknown. Coyle (1971) decided to synonymize the latter species under Antrodiaetus unicolor , but did not designate a neotype for the species. It is necessary to designate a neotype for A. unicolor at this time to establish its identity and to set a type locality for the species. A significantly larger scale study on this species is underway and preliminary data suggests that A. unicolor actually represents a complex of "cryptic species"; therefore, a fixed locality is necessary for the anticipated nomenclatural matters ahead.
We selected an adult male from DeSoto State Park in northeastern Alabama as the neotype for the following reasons: (1) male mygalomorph spiders tend to have more meaningful and useful diagnostic morphological characters; (2) to maintain the type locality of A. unicolor in Alabama; (3) most populations studied in Alabama appear relatively homogeneous and likely belong to the same “morphological” species (Coyle 1971; Hendrixson pers. obs.); (4) the population is sufficiently large (Coyle 1971; Hendrixson pers. obs.); and (5) this population of A. unicolor is likely to persist because its habitat is protected within state park boundaries.
Other specimens examined. United States : Alabama : Dekalb County : DeSoto State Park near Fort Payne ( 34.50°N , 85.62°W ): July–August 1937 ( W.B. Jones , 1 male ( AMNH ) ; ditto, October 1937 (collector unknown), 1 male ( AMNH ) ; ditto, December 1937 ( W.B. Jones ), 1 male ( AMNH ); North Carolina : Macon County : Coweeta Hydrologic Station (LTER): Coweeta Watershed unknown : 27 September– 13 October 1978 , in pitfall traps ( L. Reynolds ), 4 males ( NCSM ) . Coweeta Watershed 2 ( 35.07°N , 83.44°W ): 13 October 1978 , in pitfall traps ( L. Reynolds ), 12 males ( NCSM ) ; ditto, 27 September– 11 October 2003 , in pitfall traps ( B.E. Hendrixson & C.J. Dreiling ), 2 males ( ECU-USNM , MY 2390, 2391 ) . Coweeta Watershed 7 ( 35.06°N , 83.44°W ): 13 October 1978 , in pitfall traps ( L. Reynolds ), 1 male ( NCSM ) . Coweeta Watershed 14 ( 35.05°N , 83.43°W ): 13 September 2003 ( B.E. Hendrixson , R.E. Chester , J.L. Roberts & C.L. Spruill ), 4 females ( ECU-USNM , MY 2300-2303 ) ; ditto, 13-27 September 2003 , in pitfall traps ( B.E. Hendrixson ), 3 males ( ECU-USNM , MY 2314-2316 ) ; ditto, 27 September 2003 ( B.E. Hendrixson ), 1 male , 1 female ( ECU-USNM , MY 2317, 2323 ) .
FIGURE 2. Map of the Coweeta LTER site, showing its location in southwestern North Carolina ( NC ) and the specific watersheds from which specimens in this study were collected.
FIGURES 3-8. Neotype male of Antrodiaetus unicolor from Alabama (3-5), holotype male of A. microunicolornew species (6, 7), and female ( MY 2402) of A. microunicolornew species (8): 3, right pedipalp tibia, cymbium and bulb, prolateral aspect; 4, tibia, metatarsus and tarsus I showing mating clasper, prolateral aspect (arrow indicating presence of macroseta A on the ventral aspect of metatarsus); 5, closer view of the ventral aspect of metatarsus I (arrow indicating presence of macroseta A ); 6, right pedipalp tibia, cymbium and bulb, prolateral aspect (note relative robustness of tibia); 7, tibia, metatarsus and tarsus I showing mating clasper, prolateral aspect (arrow indicating absence of macrosetae on the ventral aspect of metatarsus); 8, spermathecae (solid lines indicate heavily sclerotized area; dotted lines indicate areas with little sclerotization). Note: apparent differences in pedipalp bulb morphology between the two species are photographic artifacts. To prevent damage to the specimens, the bulbs were not twisted to obtain the same view. No significant differences were observed between the two species. Scale bars for appendages = 2 mm ; for spermathecae = 0.5 mm .
Diagnosis. - Of the three species of Antrodiaetus currently recognized from the eastern United States (i.e., A. unicolor,A. robustus,A. microunicolornew species ), A. unicolor can be recognized by the following combination of characters: presence of macroseta A on male metatarsus I (rarely absent, or rarely with macroseta B ); at least one-fifth of macrosetae on male prolateral tibia I ensiform; presence of thickened convergent medial setae just posterior to the pedicel on the opisthosoma (on immature and female specimens). For comparisons to A. microunicolornew species , please refer to the diagnosis of that species found below.
Description. Neotype male: Coloration (in alcohol): Specimen has been preserved for over 65 years and is more or less dark reddish-brown throughout; this coloration probably is not indicative of the original spider. Prosoma: Head region slightly elevated from thoracic region. Setae moderately dense along peripheral edges of dorsal shield of prosoma; setae sparsely distributed on dorsal surface of dorsal shield of prosoma posterior to fovea. Sternum and labium moderately to densely setose. Opisthosoma: Three heavily sclerotized, completely continuous tergites on dorsal surface; posterior patch smaller than others but mostly indistinct from second. Entire opisthosomal surface densely covered with setae, interspersed with some slightly more elongated and thickened setae posteriorly; tergites accompanied by a few thickened setae. Ventral surface of opisthosoma with 30 epiandrous gland spigots located just anterior to genital opening. Chelicerae: Anterior dorsal prominence weak. Upper ectal (retrolateral) surface devoid of setae. Pedipalps (Fig. 3): Tibia moderately slender (PTiL/PTiD = 2.44). ICS tip below level of OCS; ICS tip well-sclerotized, tapered to a narrow point; OCS tip well-sclerotized, blunt, weakly serrated. Leg I: Mating clasper (located on prolateral surface of tibia) consisting of 13 ensiform, 2 attenuate macrosetae, centered at approximately 2/3 distance from proximal to distal end of tibia (Fig. 4). Prolateral, ventral, distal aspect of tibia with a macroseta. Retrolateral, ventral aspect of tibia with 7 ensiform macrosetae; distal-most macroseta of group positioned at approximately 4/5 of distance from the proximal to distal end of tibia. Macroseta A (Coyle 1971, fig. 70) present on ventral aspect of metatarsus (Figs. 4-5); a moderately thickened seta is located at position B, but is not considered a macroseta. Metatarsus moderately sinuous in ventral view. Measurements (mm): CL = 6.13; SL = 3.35; SW = 2.90; CT (l/r) = 10/9; PFeL = 3.65; PTiL = 3.30; PTiD = 1.35; IFeL = 5.85; ITiL = 4.05; IMeL = 5.00; ITaL = 2.85; ALD = 0.40; AMD = 0.12; ALS = 0.42; AMS = 0.20; OQW = 1.22.
Variation. Males from DeSoto: Three additional adult males of Antrodiaetus unicolor from the new type locality at DeSoto State Park were examined during the course of this study. They do not differ significantly from the neotype in any important characters. The number of macrosetae making up the mating clasper is variable. One specimen also possesses macroseta B on the ventral surface of metatarsus I. A summary of measurements can be found in Table 1.
Specimens from Coweeta: A total of 23 adult males and five adult females were studied from Coweeta. Males compare favorably to those at DeSoto State Park. Most of the males possessed macroseta A on the ventral surface of metatarsus I; four males also had macroseta B; and one male also had macrosetae B and F. Two males collected during the 13-27 September 2003 pitfall trap series ( MY 2314, 2316) were divergent from the others
by the following characters: (1) the absence of macrosetae on the ventral surface of metatarsus I; (2) darker coloration; (3) legs slightly more setose; (4) absence of a macroseta on the prolateral, ventral, distal aspect of tibia I (this macroseta is absent in a few other males as well); and (5) mating clasper macrosetae centered at approximately 1/2 the distance from the proximal to distal end of tibia I. These two specimens are herein referred to as Antrodiaetus unicolor because of their large size ( CL 7.30 and 6.30 mm , respectively) and breeding season, but they will be studied in greater detail at a future date. The females do not differ from one another in a meaningful way. A summary of measurements can be found in Tables 1 and 2.
TABLE 1. Selected measurements (in mm) for adult male Antrodiaetus . The first row for each species shows the range of measurements observed; the second row indicates the mean and standard deviation in the measurements for the given sample size. AL = males of A. unicolor from DeSoto State Park in northeastern Alabama; COW = males of A. unicolor from the Coweeta LTER site in southwestern North Carolina.
|A. unicolor ( AL ) n = 4||5.44-6.38 6.05 ± 0.42||5.15-5.85 5.68 ± 0.35||3.70-4.05 3.94 ± 0.16||4.50-5.00 4.78 ± 0.21||2.50-2.85 2.69 ± 0.14||3.30-3.65 3.55+/-0.17||2.95-3.25 3.18 +/- 0.16||1.15 –1.35-3.55± 1.29 +/- 0.09|
|A. unicolor ( COW ) n = 10||5.63-7.06 6.47 ± 0.42||5.05-6.20 5.81 ± 0.35||3.60-4.35 4.07 ± 0.25||4.30-5.25 4.80 ± 0.27||2.35-2.75 2.57 ± 0.13||3.30-3.90 3.71+/-0.19||3.05-3.60 3.35 +/- 0.15||1.35 –1.50-3.71± 1.43 +/- 0.06|
|A. microunicolornew species n = 10||3.75-4.50 4.15 ± 0.29||3.35-4.10 3.72 ± 0.25||2.40-2.85 2.64 ± 0.14||2.75-3.20 3.02 ± 0.16||1.60-1.85 1.74 ± 0.09||2.25-2.70 2.47 ± 0.15||2.05-2.35 2.23 ± 0.11||0.95-1.10 1.05 ± 0.06|
TABLE 2. Selected measurements (in mm) for adult female Antrodiaetus . The first row for each species shows the range of measurements observed; the second row indicates the mean and standard deviation in the measurements for the given sample size. COW = females of A. unicolor from the Coweeta LTER site in southwestern North Carolina.
|A. unicolor ( COW ) n = 5||7.10-8.20 7.80 ± 0.48||3.70-4.40 4.10 ± 0.29||3.20-3.80 3.52 ± 0.29||5.05-5.85 5.47 ± 0.33||3.00-3.60 3.35 ± 0.25||3.05-3.60 3.36 ± 0.23|
|A. microunicolornew species n = 5||5.25-6.88 5.82 ± 0.69||2.88-3.63 3.14 ± 0.34||2.44-3.13 2.66 ± 0.29||3.70-4.65 4.04 ± 0.38||2.30-2.80 2.50 ± 0.20||2.10-2.55 2.27 ± 0.21|
|A. unicolor ( COW ) n = 5||1.60-1.90 1.78 ± 0.13||4.95-5.65 5.30 ± 0.33||3.00-3.40 3.20 ± 0.19||4.20-4.95 4.66 ± 0.34||1.70-1.95 1.83 ± 0.10|
|A. microunicolornew species n = 5||1.25-1.50 1.34 ± 0.11||3.50-4.50 3.85 ± 0.41||2.05-2.45 2.19 ± 0.17||2.85-3.60 3.12 ± 0.30||1.30-1.50 1.37 ± 0.08|
Distribution . - Widespread throughout the eastern United States, particularly in the southern and central Appalachian Mountains. Please refer to Map 1 in Coyle (1971) for a more thorough picture of the known distribution of this species.