F. A. Coyle.
Systematics of the Trapdoor Spider Genus Aliatypus (Araneae: Antrodiaetidae).
Psyche 81:431-500, 1974.

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SYSTEMATICS OF THE TRAPDOOR SPIDER GENUS ALIA TYPU5 ( ARANEAE : ANTRODIAETIDAE) * Department of Biology, Western Carolina University, Cullowhee, North Carolina, 28723
Aliatypus species are all rather stocky mygalomorph spiders (Figs. 45-49) which construct a burrow with a trapdoor entrance from which they capture prey. In general morphology and behavior, Aliatypus bears striking resemblance to the distantly related trapdoor spider family Ctenizidae, but this similarity is clearly the result of convergent, or at least parallel, evolution; Aliatypus is an atypoid mygalomorph taxon most closely related to Antrodiaetus, Atypoides, and the Mecicobothriidae. Allatypus species appear to be restricted to California and Arizona
(Maps 1-4) where they live in ravine
banks, road banks, or other slopes in habitats ranging from hot, dry sagebrush scrub communities to wet coast redwood forests and cool California red fir mountain forests. They are among the most abundant trapdoor spiders in California. Aliatypus has been badly neglected; only one species has been described (Banks, 1896; Smith, 1908) and little natural history information has been published (Smith, 1908 ; Gertsch, 1949; Coyk, 1971). During the last seven years a concerted collecting effort, largely by Wendell Icenogle and myself, has increased the availability of adult specimens from a dozen to 330 and has thereby made pos- sible this revision. My chief goal in this study has been to define accurately the species limits by means of an analysis of variation. The methods employed are essentially those of my earlier studies (Coyle 1968, 1971) and are summarized in the Methods section of this paper. Discussions of variation patterns are included in order to improve our understanding of geographic variation in mygalo- morph spiders and guide future research on Alwtypus. The consid- erable amount of behavioral and ecological data which has been collected will be published separately in a paper on AIiatypus natural history.
*Manuscript received by fhe editor January 1, 1975. 43 1




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432 Psyche [September-December
I hope that these studies of Aliatypus will stimulate others to investigate these fascinating spiders.
Considerably more collecting
is necessary before Aliatypus systematics can be confidently under- stood. As pointed out in the discussions of variation, small sample sizes and sizeable geographic gaps from which no samples are avail- able have greatly limited the strength of some of my conclusions. The variation discussions, locality records, and distribution Maps 2-4- (Map 4 marks the distribution of unidentifiable Aliatypus speci- mens.) should help direct future collecting efforts. Willis Gertsch first recognized the potential diversity within AUatypus and suggested that I revise the genus. Wendell Icenogle deserves tremendous credit for the hours he labored collecting about 55 percent of the specimens upon which this study is based. He was
the first collector of five new species. Without his field work this study would be very incomplete. Jim Horton, my department head during most of this research, provided needed space and release time. I thank the following individuals and institutions for loans of Aliatypus specimens: William Azevedo, Michael Bentzien, Patrick Craig, Willis Gertsch (American Museum of Natural History), Wendell Icenogle, Herbert Levi (Museum of Comparative Zoology), Patrick Marer, Robert Schick (California Academy of Sciences), and Me1 Thompson. This research and its publication have been supported by a grant (GB-34128) from the National Science Foundation.
PHYLOGENY
AZiatypusJ Antrodiaetus, Atypoides, the Mecicobothriidae, and the Atypidae form a distinct monophyletic taxon ( Coyle, I 97 I ) .
Aliatypus is probably an old group, so that the details of its relation- ship to these other atypoid mygalomorph taxa are not now clear. The question of whether Aliatypus is more closely related to Antro- diaetus and Atypoides or to the mecicobothriids was discussed earlier (Coyle, 1971)) but will remain unresolved until after the completion of a careful comparative study of all atypoid mygalomorphs. In Figure I I have presented a hypothetical phylogeny of the genus Aliatypus. This speculation is based upon a comparison of character states in living Aliatypus species and related genera. It is.



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Coyle - Genus Aliatypus
FIGURE 1
Figure 1: Suggested phylogeny of Aliatypus species. 1. Character states of hypothetical ancestral stock: No ICS keel or OCS keel. Seminal receptacles with moderately long, sinuous, non-tapering stalks and medium sized bulbs. Posterior sigilla small and well separated. Legs of moderate
length. Thoracic groove a deep pit. Leg I setation as in majority of species. Moderately large body. 2. Seminal receptacle stalks become short and straight. Legs become proportionately shorter. 3. Posterior sigilla enlarge. Thoracic groove lost. Leg I setation changes. 4. Pos- terior sigilla enlarge. Legs become proportionately shorter. Become adapted to dryer habitats. 5. Become adapted to more humid and cooler habitats. 6. ICS keel develops. 7. Seminal receptacle stalks become tapered. 8. Con- ductor tip changes form. Body size reduced. 9. Seminal receptacle stalks
become less elongate and less sinuous. Body size reduced. 10. Body size reduced.
meant to be a useful working hypothesis, subject to revision. Char-
acters which were relied upon most heavily are palpus form, seminal receptacle form, and posterior sigilla size and placement. The actual direction of evolution in some characters may well be the reverse of those suggested. It is certain that Aliatypus contains two distinct groups of closely related species - A. californicus, A. janus, A. iso- lotus, A. aquilonius, and A. gnomus on the one hand and A. tro- phonius, A. erebus, A. plutonis, and A. torridus on the other - and two distinct species, A. gulosus and A. thompsoni, each rather dis- tantly related to all the others.




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434 Psyche [September-December
GEOGRAPHIC VARIATION AND SPECIATION
As is the case in Antrodiaetus (Coyle, 197 I ), Atypoides (Coyle, 1968), and probably most other burrowing mygalomorph genera (See, for example, Main, 1957; Loksa, 1966; and Forster and Wilton, 1968.)) there is considerable geographic variation in some species of Al'wtypus. Detailed descriptions of these geographic vari- ation patterns can be found in the Taxonomy section. My purpose here is to consider some of the causes olf these patterns. The environmental tolerance ranges and dispersal ability of a species are key factors in determining what environmental conditions constitute barriers which can fragment and isolate its populations so that genetic divergence can take place. Little pertaining specifically to Aliatypus dispersal can be added to my earler discussion of dis- persal ability in antrodiaetids (Coyle, I 97 I ) . In summary, the prob- ability of successful colonization of distant localities by long distance aerial dispersal is extremely low; aquatic rafting, short distance spiderling dispersal, and male wandering are probably the only im- portant means of dispersal under natural conditions. As in Antro- dwetus and Atypoides, environments with very low humidity, such as deserts or semiarid grasslands, are the outstanding barriers to dispersal and thus gene flow in Aliatypus. However, some species of Aliatypus, notably A. plutonis and A. torridus, are less well restricted by dry barriers than are most other antrodiaetids. The following discussions, although partly speculation, should, like any working hypotheses, help direct 'further research. Frequent refer- ral to Map I will help to understand them. The Central Valley of California, a semiarid grassland in its recent natural state, appears to be a strong barrier to gene flow between coastal and 'Sierran populations of both Aliatypus californicus and AZiatypus erebus. The genetic discontinuity between these popu- lations may even be great enough to merit calling them incipient species. A similar situation exists in Atypoides riversi (Coyle, 1968 and 197 I ) . Apparently, during Pleistocene glacial periods when the climate was wetter and cooler, dispersal of these species occurred across favorable wooded parts of the Central Valley. The recent discovery of isolated A. californicus and A. riversi populations in the Sutter Buttes of the Central Valley indicates that this was once part of such a corridor allowing gene flow across the valley. Similar dis- persals across the Central Valley during Pleistocene glacial periods are also indicated by distribution patterns of the salamander genera Ensatina and Taricha, which, like Aliatypus, require rather mesic habitats (Stebbins, 1949; Riemer, 1958). I suspect that the antro-



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19741 Coyle - Genus Aliatypus 43 5
Map 1. Kn,own distribution ranges of Aliatypus species in relation to present major arid habitat barriers which formed during the retreat of the Wisconsin glaciation.
diaetid trans-valley connections existed during the most recent (Wis- consin) glacial period 'and consequently became severed as recently as I 3,000 years ago. Perhaps the A. californicus population at Mari- posa, which is phenotypically more distinct from the coastal popula- tion than is the north Sierran population, was last connected with the coastal population during an earlier glacial period; or perhaps its trans-valley connections were simply severed earlier during the retreat of the last (Wisconsin) glacial period than were those of the north Sierran populations. Perhaps continued expansion of habitat barriers during the present post-glacial period has tended to restrict gene flow between the morphologically divergent northern populations of A. erebus and its south Sierran populations. There is much geographic variation in Aliatypus janus, but the samples are so small and scattered that it is difficult to recognize important barriers to gene flow. The northernmost samples probably



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436 Psyche , ' [September-December
represent the kind of semi-isolated, genetically divergent, peripheral populations found in many species. Aliatypus thonzpsoni variant populations are also at the periphery of the species range, where suitable habitats are probably uncommon and semi-isolated. The Tehachapi Mountains apparently provide (or recently provided) an east-west corridor of favorable habitats for the dispersal of A. janus and A. thowsoni between the southern end of the Sierra Nevada Mountains and the coastal mountain ranges. The morphologically
divergent nature of the A. thonzpsoni samples at Tehachapi and in the southern end of the Sierra Nevada Mountains indicates that this corridor is not currently supporting much dispersal. The phenotypic differences between the two known Aliatypus isolatus populations in Arizona are almost certainly caused by the disruption of gene flow after the recent (Wisconsin) glacial period as desert and grassland barriers expanded all over the Southwest to isolate various mesic mountain habitats. Pollen analyses (Martin and Mehringer, I 965 ) demonstrate that during the Wisconsin glacial period (which apparently lasted in that area until about 13,000 years ago), woodland and forest habitats favorable for A. isolatus extended continuously throughout western and northern Arizona. Thus the similar geographic variation patterns in A. isolatus and Antrodiaetus apachecus (Coyle, 1971) probably have a common cause. The extreme similarity of allopatric Aliatypus janus and Aliatypus isolatus, when viewed with Southwest pollen analyses (Martin and Mehringer,
1965) in mind, leads to the conclusion that these two species were formed when a recent interglacial expansion of the Sonoran and Great Basin Deserts severed a previously widespread ancestral population. Convincing evidence that I 7,000 to 23,000 years ago (during the Wisconsin glacial period) woodland extended continuously from current A. isolatus localities to the present range of A. janus, strongly indicates that these sister species may be only 15,000 years or so old. Indeed, it is possible that genetic divergence has not even progressed far enough for the development of repro- ductive isolating mechanisms.
There are three other pairs of closely related Aliatypus species- A. janus and A. aquilonius, A. californicus and A. gnomus, and A. erebus and A. trophonius - which are not as similar as A. jams is to A. isolatus. It is possible that each of these pairs originated from a trio of ancestral speci,es fragmented by arid barriers, such as the present Central Valley, during an earlier Pleistocene interglacial. Interestingly, each of these pairs consists of a large and a small species.



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C o ~ l e ~ Genus Aliaty~s
COLLECTING METHODS
Because of their covert behavior, AZiatypus spiders are rarely col- lected except when one concentrates on special collecting strategies. Banks and slopes of promising habitats (to be described thoroughly in a paper on Aliatypus natural history) are best searched in daylight by carefully examining suitable microhabitat surfaces for the out- line of a closed trapdoor. However, whenever the trapdoors are sealed, such as during dry periods, they may become covered with loose soil particles or other debris; carefully shaving away the top layer of soil may then be the only way to locate burrows. Night collecting is usually less satisfactory than daytime collecting since even unsealed Aliatypus doors are only cracked open at night and not easily located with artificial light. At night it is sometimes pos- sible to trap active spiders at their burrow entrances by thrusting a knife blade into the soil and across the burrow lumen just below the spider, but frequently the soil is too hard. More information can be gained by careful excavation of the burrow in daylight. An army trench shovel, a small, chisel-head, rock hammer, a large pocket knife, and pruning shears are all usemful for excavating in the often hard and root-bound soil.
Penultimate males, easily recognized by their swollen pedipalpal tarsi, will often molt to adulthood if kept in a cool, humid, and dark environment. Just before and during the mating season (usually during the wet fall and winter months) recently matured males may be found in their burrows prior to abandoning them. Wandering males are best collected at night by hand or with pitfall traps in dense burrow aggregations during opti- mum mating weather.
ANALYSIS OF VARIATION
I have examined the taxonomy of Aliatypus by means of an analy- sis of variation nearly identical to the analysis employed in my re- visions of Antrodiaetus (Coyle, I 97 I ) and Atypoides ( Coyle, 1968). Such an analysis largely overcomes difficulties posed by the relatively simple reproductive anatomy, by the instar heterogeneity of adult female samples, and by heightened geographic variation, difficulties which appear to be common to most mygalo'morph spider taxa. The material analyzed consists of 252 adult females and 78 adult males. The sample size for each species is indicated in Tables I and 2. Initially, variation in a large number of qualitative and quantita- tive characters was briefly surveyed, and from these characters the diagnostically most promising were selected and their variation studied



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438 Psyche [September-December
in depth. Variation of the quantitative characters (measurements, meristic characters, and ratios formed from these) was analyzed with the aid of an IBM 360 Model 30 computer. A Fortran IV program directed the computer to calculate the mean and standard deviation of each character for each local population sample of each sex and for certain groupings of local samples into larger in'fraspecific samples or species samples. The computer then compared these samples pair- wise in any desired combination, giving for each character for each comparison a value of the distinctness of the two samples. This "distance" value equals the difference between the means of the two samples divided by the sum of their standard deviations. This variation analysis was performed with the following number of characters: 23 measurements, one meristic character, and 39 ratios for males; 20 measurements, six meristic characters, and 50 ratios for females. The measurements and meristic characters were defined so as to be clearly delimited. Their abbreviations and definitions are as follows (see Figs. 2-7) :
PCA
Figures 2-7: Measurements used in Aliatypus revision. See text for definitions. Figures 8-9 : Macrosetae types. 8 : ensiform. 9 : attenuate. CL
Maximum length of carapace measured as distance (along median longitudinal axis) between lines tangent to anterior- most and posteriormost edges of carapace, with lateral border of carapace in horizontal plane.
PCL
Length of pars cephalica measured as distance 'from anterior edge of thoracic groove along median longitudinal line. CW
Maximum width of carapace along line perpendicular to median longitudinal axis.




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19741 Coyle - Genus Aliatypus 439
IFL
Length of femur I taken as length of straight line connect- ing the proximal and distal points of articulation. All leg and pedipalp segment length measurements were made in side view along retrolateral surface of appendages after removing them from spid~er.
ITL
Length of tibia I taken as length of straight line connect- ing proximal and distal points of articulation. IML Length of metatarsus I taken as length of straight line con- necting proximal point of articulation with distalmost point of segment.
ITarL Length of tarsus I taken as length of straight line connect- ing most proximal exposed point of tarsus with distalmost point of dorsal surface.
IVFL, IVTL, IVML, IVTarL
Leg IV segment lengths meas-
sured in same manner as corresponding leg I segments. PFL
PPL
PTL
PTX
PTT
PED
PCA
SL
sw
PSS
PSL
OQW
ALS
ALD
AMS
Length of pedipalpal femur measured same as IFL. Length of pedipalpal patella measured as straight line dis- tance from proximal to distal end along dorsal surface. Length of pedipalpal tibia measured same as ITL. Distance from proximal point of articulation on tibia to point where PTT line intersects PTL line. Maximum dimameter, taken perpendicular to line defining PTL of pedipalpal tibia in lateral view. Straight line distance from base of embolus to tip of con- ductor.
Maximum distance from PED line to outer edge of OCS along line perpendicular to PED line.
Maximum length of sternum on line parallel to median longitudinal axis. Anterior border of sternum is its pointed anterior extension lateral to labium.
Maximum width of sternum perpendicular to line defining SL.
Minimum distance between posterior sigilla. Maximum diameter of right posterior sigillum. Maximum width of eye group (ocular quadrangle) on line perpendicular to median longitudinal axis of carapace. All eye measurements are made in dorsal view with lateral border of carapace horizontal.
Minimum distance between anterior lateral eyes. Maximum diameter of left anterior lateral eye. Minimum distance between pupils (light colored sauoer- shaped central area of eye) of anterior median eyes.



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440
AMD
EGS
CTP
CTR
CMT
PTS P
PTSR
IMS
Psyche [September-December
Transverse diameter of left anterior median eye pupil. Number of epiandrous gland spigots. These are located just anterior to genital opening on abdomen of adult males. Number of cheliceral teeth in prolateral macrotooth row on left chelicera.
Number of cheliceral teeth in retrolateral row of smaller macroteeth on left chelicera.
Number of cheliceral microteeth between these two rows on left chelicera.
Number of ensiform macrosetae on prolateral surface of tarsus of female pedipalp.
Number of ensiform macrosetae on retrolateral surface of tarsus of female pedipalp.
Number of ensiform macrosetae on metatarsus of leg I of cflemale.
All measurements and counts were performed by myself with the same Wild M-5 stereomicroscope with 20X eyepieces and an eye- piece micrometer scale. The measurements are accurate to one mi- crometer unit for each of the three different powers of magnification used. One micrometer unit had the following values for the 'follow- ing characters: 0.0770 mm for CL; 0.0385 mm for PCL, CW, SL, SW and all leg and pedipalp segment lengths; and 0.0092 mm for PTT, FED, PCA, PSS, PSL, and all eye measurements. A female specimen was included in a population sample only if it was reproductively active (with maturing eggs in abdomen or brood in burrow) or had a longer carapace than the smallest reproductively active female in that sample. Many first adult instar females, a few older adult instar females, and rarely a large immature female make up the portion of a sample which is not reproductively active. MORPHOLOGICAL TERMINOLOGY
Setae. Postocular setae form a longitudinal row or longitudinal cluster along the m>edian longitudinal axis of the pars cephalica just behind the eye group. A macroseta is a very large seta. Called spines by many authors, these macrosetae are attached to the exoskeleton proper by means of an obvious socket which allows for some move- ment. An ensiform macroseta is one which tapers rather abruptly at its terminal end and is therefore rigid for its entire length (Fig. 8). An attenuate macroseta tapers gradually and is therefore very slender distally (Fig. 9).




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19741 Coy le - Genus AZiatypus 44 1
Palpus. The conductor of the Aliatypus palpus (Fig. 97) consists of an inner conductor sclerite (ICS) and an outer conductor sclerite (OCS) which lies outside and partly cradles the ICS and the em- bolus. The ICS base is forked, with the more well developed of the two branches being called the ftroximal branch. Female genitalia. In Aliatypus the bursa copulatrix, which opens just anterior and ventral to the uterus opening in the epigastric fur- row, is bilobed and weakly sclerotized.
The four semi~zaZ receptacles
(Fig. 163) are functionally paired so that the two on the right side open close to one 'another into the right lobe of the bursa copulatrix and the other two open together into the left lobe. Each seminal receptacle is weakly sclerotized and consists of a narrow stalk and a distal expanded bulb. The seminal receptacle is either homogeneously sclerotized or the bulb is slightly less sclerotized than the stalk. Aliatypus stalks are usually sinuous, frequently even highly looped or coiled. These loops and coils are not confin'ed to a single plane and are often irregular so that the degree of looping or coiling is very difficult to quantify. It is, however, possible to make a rough quanti- tative comparison by counting the number of bends per stalk, as is done in Figure 163, when the stalk is treated as a two-dimensional structure.
Abdominal termites. The anterior portion o'f the abdominal dorsum of Aliatypus is provided with one or more segmentally arranged, rather heavily sclerotized patches which are presumably vestigial ter- gites (Figs.45-49). These tergites are numbered from antlerior to posterior, tergite I, trrgite 11, and te+te III. Tergite I1 is always present in both sexes and is always larger than tergites I or 111. METHODS OF PRESENTATION
Type specimens. The holotypes of all species described in this paper are deposited in the Museum of Comparative Zoology. All paratypes are from the type locality and are labeled as paratypes. The paratypes for each species are deposited in about equal numbers in the Museum of Comparative Zoology and the American Museum of Natural History. Quantitative character values are given for each holotype in Table 3.