Antrodiaetus unicolor

Hendrixson, BRENT E. & Bond, Jason E., 2005, Two sympatric species of Antrodiaetus from southwestern North Carolina (Araneae, Mygalomorphae, Antrodiaetidae), Zootaxa 872, pp. 1-19: 4-10

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Antrodiaetus unicolor


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), male neotype (herein designated) ( AMNH).GoogleMaps 

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);GoogleMaps  ditto, October 1937 (collector unknown), 1 male ( AMNH);GoogleMaps  ditto, December 1937 (W.B. Jones), 1 male ( AMNH);GoogleMaps  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);GoogleMaps  ditto, 27 September– 11 October 2003, in pitfall traps (B.E. Hendrixson & C.J. Dreiling), 2 males ( ECU-USNM, MY 2390, 2391).GoogleMaps  Coweeta Watershed 7 (35.06°N, 83.44°W): 13 October 1978, in pitfall traps (L. Reynolds), 1 male ( NCSM).GoogleMaps  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);GoogleMaps  ditto, 13-27 September 2003, in pitfall traps (B.E. Hendrixson), 3 males ( ECU-USNM, MY 2314-2316);GoogleMaps  ditto, 27 September 2003 (B.E. Hendrixson), 1 male, 1 female ( ECU-USNM, MY 2317, 2323).GoogleMaps 

Diagnosis. - Of the three species of Antrodiaetus  currently recognized from the eastern United States (i.e., A. unicolor,  A. robustus,  A. microunicolor  new 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. microunicolor  new 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.

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.


USA, New York, New York, American Museum of Natural History


USA, Raleigh, North Carolina, North Carolina State Museum of Natural Sciences


Australia, New South Wales, Sydney, Australian Museum