AMERICAN MUSEUM ,.~~~~~~~Novitates1 PUBLISHED BY THE AMERICAN MUSEUM OF,NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET NEW YORK. N.Y. 10024 U.S.A. NUMBER 2704 SEPIEMBER 22, 1980 WILLIS J. GERTSCH AND NORMAN I. PLATNICK A Revision of the American Spiders of the Family Atypidae (Araneae, Mygalomorphae) AMERICAN MUSEUM Norntates PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. 10024 Number 2704, pp. 1-39, figs. 1-60 September 22, 1980 A Revision of the American Spiders of the Family Atypidae (Araneae, Mygalomorphae) WILLIS J. GERTSCH1 AND NORMAN I. PLATNICK2 ABSTRACT The eight known New World species of Atyp- genus Sphodros Walckenaer. Sphodros bicolor idae are diagnosed, described, and assigned to and S. milberti are newly synonymized with S. two genera on the basis of genitalic and somatic rufipes. Four new species are described: S. pai- characters. Only one American species, Atypus sano from Texas and Tamaulipas, Mexico; S. fit- snetsingeri Sarno, belongs to the Holarctic genus chi from Nebraska, Kansas, Oklahoma, and Ar- Atypus Latreille. The nominal species Atypus ab- kansas; S. atlanticus from Virginia, Illinois, boti (Walckenaer), A. rufipes Latreille, A. bicolor North Carolina, and Georgia; and S. coylei from Lucas, A. milberti (Walckenaer), and A. niger South Carolina. Hentz are transferred to the endemic Nearctic INTRODUCTION The name Atypidae is used here in the tures plesiomorphic for these spiders. Among sense established by Simon (1903), who re- these are the presence of a large tergite on stricted the family to a small group of dis- the dorsum of the abdomen (figs. 3-6), of six tinctive mygalomorphs with representatives spinnerets (fig. 23) still maintained as in most in both hemispheres. The atypids are bur- Antrodiaetidae, Mecicobothriidae, and prim- rowers that spin a tough tubular web in the itive Dipluridae, the doubled nature of the soil and prolong and camouflage an aerial elements of the male palpus, both embolus segment as a trap for wandering insects. The and conductor being present, the moderately short aerial tube of the European Atypus lies wide separation of the anal tubercle from the on the soil, whereas the long tube of the spinnerets, and the presence of a swollen American Sphodros is usually tied vertically palpal tarsus in penultimate males. These to the side of a tree (figs. 1, 2). The family features have all been modified in higher my- represents an ancient branch of the infraor- galomorphs. On the other hand, the quite der Mygalomorphae still retaining many fea- successful atypids have derived features in 1 Curator Emeritus, Department of Entomology, American Museum of Natural History. 2 Associate Curator, Department of Entomology, American Museum of Natural History; Graduate Faculty in Biology, City College, City University of New York. Copyright © American Museum of Natural History 1980 ISSN 0003-0082 / Price $2.60 2 AMERICAN MUSEUM NOVITATES NO. 2704 both their morphology and especially their for there are two apparent synapomorphies ingenious technique of capturing prey. uniting the three genera and none (that we The present systematic account of the are aware of) contradicting that relationship. Nearctic Atypidae supplants an earlier work The first of these synapomorphies is the clas- (Gertsch, 1936) in which the three species sical one: the prolongation of the inner por- then known were described and illustrated. tion of the palpal coxa into a distinct lobe Since that time, only one additional species, comparable to the endite of araneomorphs. Atypus snetsingeri Sarno from Pennsylva- As noted by Simon (1892), the few other nia, has been described, but much additional mygalomorphs (like Paratropis and Actino- information has accumulated. Important new pus) that have a coxal lobe at all do not share collections of these relatively rare spiders, the extreme prolongation of the lobe found which are numerous only in rather restricted in Atypus, Sphodros, and especially Cal- habitats, have doubled the size of the Amer- ommata. The second synapomorphy uniting ican fauna. Our species other than A. snet- the atypid genera is the structure of the pos- singeri are now assigned to the genus Spho- terior median spinnerets, which are ex- dros in recognition of differences in their tremely wide and bear obliquely triangular male and female genitalia and their greater tips (fig. 23); so far as we are aware, such degree of sexual dimorphism (the males usu- peculiarly shaped posterior median spinner- ally being significantly smaller and some- ets are not found in any other spiders. times brightly colored). In addition, the spe- Within the Atypidae, each of the three cific names of two of the previously known genera is distinguished by a unique type of species have had to be changed because of spermathecal structure. In Atypus, there are new synonymies; both S. bicolor and S. mil- two broad plates each bearing two or more berti are now regarded as synonyms of S. small receptacula (fig. 19). In Calommata, rufipes, and S. niger is recognized as the val- there are four spermathecae, each bearing id name for our most northern species. several closely packed terminal receptacula positioned in a cauliflower-like arrangement RELATIONSHIPS (Kraus, 1978, fig. 13 of C. simoni; we have observed the same structure in C. signatum Traditionally, the Atypidae has been divid- and C. sundaicum). In Sphodros, there are ed into two genera, Atypus and Calommata. four spermathecae, each highly coiled and However, as Kraus and Baur (1974) have in- without distinct receptacula (figs. 29, 58). dicated, two very different types of sper- There is growing evidence (Kraus, 1978; R. mathecae and palpi are found among the R. Forster, personal commun.) that the ple- species previously assigned to Atypus. siomorphic form of the female genitalia for Those authors suggested that only Palaearc- spiders is a single spermatheca bearing nu- tic species actually belong to Atypus, in merous receptacula. If so, the spermathecal which case the generic name Sphodros could arrangement of Atypus represents the most be revived for the Nearctic species. As plesiomorphic form within the Atypidae, but shown below, the division is not quite so pre- the details of that structure (particularly the cise geographically; although Sphodros is two broad plates) argue as strongly for the exclusively Nearctic, one species of Atypus monophyly of Atypus as the unique types of is found in America as well. Kraus and Baur spermathecal morphology of Calommata (1974, p. 88) also suggested that Calommata and Sphodros do for the monophyly of those should not be included in the Atypidae, but groups. they did not indicate whether they believe The question thus arises as to the interre- only that Calommata is different from Aty- lationships of the three atypid genera. An pus and Sphodros or that it is actually more answer is difficult to obtain, both because of closely related to some other group of spi- the absence of a well-corroborated hypoth- ders than to those genera. At any rate, we esis identifying the closest relatives of the believe Simon's (1903) hypothesis of the Atypidae, and the difficulty of finding hom- composition of the Atypidae to be correct, ologs of some atypid features in other my- 1980 GERTSCH AND PLATNICK: ATYPIDAE 3 FIGS. 1, 2. Pursewebs of Sphodros from Florida; photographs by H. K. Wallace. 1. S. abboti. 2. S. rufipes. 4 AMERICAN MUSEUM NOVITATES NO. 2704 3., 4a 4~~~~~~~~~4 4~~~_~ FIGS. 3, 4. Sphodros abboti from Florida; photographs by H. K. Wallace. 3. Male. 4. Female. 1980 GERTSCH AND PLATNICK: ATYPIDAE 5 J&,e'''w'g'S r - FIGS. 5, 6. Sphodros rufipes from Florida; photographs by H. K. Wallace. 5. Male. 6. Female. 6 AMERICAN MUSEUM NOVITATES NO. 2704 galomorphs. The Atypidae has most fre- tarsus of females; and the dorsally directed quently been associated with the chelicerae, elongated palpal trochanter, and Antrodiaetidae and Mecicobothriidae, but greatly elongated posterior tarsi of males). the characters used to define this group (the Similarly, the ridged borders of the sternum Atypoidea) have been shown to be plesio- of male Atypus (fig. 14) are unique to that morphic (Platnick, 1977) and the Mecico- genus. bothriidae have been hypothesized to be Among possible synapomorphies, the more closely related to the Dipluridae change to a 2+2 spermathecal arrangement (Gertsch and Platnick, 1979). We are not would most parsimoniously link Sphodros aware of any derived characters unique to and Calommata, a hypothesis that is also the Atypidae plus Antrodiaetidae, and it may supported by the much greater degree of sex- be that the atypids represent the sister group ual dimorphism found in those two genera. of all other mygalomorphs. Atypus is the The palpal structure might be thought to con- only mygalomorph genus known to approach tradict this arrangement, as Calommata re- the putatively plesiomorphic form of female sembles Atypus rather than Sphodros in genitalia described above and found in at having a short, straight embolus (in Spho- least some Mesothelae; other mygalomorph dros, the embolus is longer and curved, fit- genera have either four separate spermathe- ting inside an elaborate conductor instead of cae (in the "2+2" arrangement defined by resting on it). There are few other spiders Kraus, 1978) or a more derived arrangement. with palpi similar enough to those of atypids If the Atypidae is monophyletic, then the to provide useful outgroup comparisons, and change to a 2+2 arrangement is most parsi- even they suggest no resolution as both con- moniously considered a synapomorphy link- ditions occur within the Antrodiaetidae and ing all the non-atypid mygalomorphs (with the Mecicobothriidae. More informative may parallelism within the Atypidae and, of be the variation within Sphodros itself. Most course, the Araneomorphae). This rather of the species of Sphodros are united by the tenuous hypothesis is also supported by the peculiar shape of the male palpal tibia, which work of Yoshikura (1958), who found that is dorsally expanded for the distal four-fifths the mygalomorphs whose development has of its length (fig.