Cloacal Anatomy of Female Salamanders of the Plethodontid Subfamily Desmognathinae ( Amphibia: Urodela) Author(S): David M

Home , Cloaca, Salamandroidea

Cloacal Anatomy of Female Salamanders of the Plethodontid Subfamily Desmognathinae ( Amphibia: Urodela) Author(s): David M. Sever and Stanley E. Trauth Source: Transactions of the American Microscopical Society, Vol. 109, No. 2 (Apr., 1990), pp. 193- 204 Published by: Wiley on behalf of American Microscopical Society Stable URL: http://www.jstor.org/stable/3226814 Accessed: 30-06-2015 16:08 UTC

REFERENCES Linked references are available on JSTOR for this article: http://www.jstor.org/stable/3226814?seq=1&cid=pdf-reference#references_tab_contents

You may need to log in to JSTOR to access the linked references.

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://www.jstor.org/page/ info/about/policies/terms.jsp

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected].

Wiley and American Microscopical Society are collaborating with JSTOR to digitize, preserve and extend access to Transactions of the American Microscopical Society. http://www.jstor.org

This content downloaded from 147.174.85.132 on Tue, 30 Jun 2015 16:08:50 UTC All use subject to JSTOR Terms and Conditions Cloacal Anatomy of Female Salamanders of the Plethodontid Subfamily Desmognathinae (Amphibia: Urodela)'

DAVID M. SEVER AND STANLEY E. TRAUTH

Department of Biology, Saint Mary's College, Notre Dame, Indiana 46556 and Department of Biological Sciences, Arkansas State University, State University, Arkansas 72467, U.S.A.

Abstract. The cloacae of females from the 11 currently recognized species in the salamander genus Desmognathus and from the monotypic genera Leurognathus and Phaeognathus were examined by light microscopy after preparation of microscope slides by standard techniques using paraffin-embedded tissues. Analyses included three-dimensional reconstructions of serial sections. All species possess spermathecae consisting of acini for sperm storage that evaginate from a common tube that passes into the cloaca. In P. hubrichti, the common tube passes horizontally into a cloacal chamber recess medial to the distal ends of the oviducts, and the spermathecae are anterior to the common tube. In the other species, no recess exists, the common tube passes ventrally into the posterior cloacal tube or anterior cloacal chamber, and the spermathecae are posterior to the common tube. Rudimentary cloacal glands called dorsal glands and ventral glands, which are symplesiomorphic characters for plethodontids, occur in some desmognathines. These glands vary from numerous in P. hubrichti and in large aquatic species (D. brimleyorum, D. monticola, and D. welteri) to absent in small terrestrial species (D. aeneus, D. wrighti). An anterior closed portion of the cloaca, the cloacal tube, is absent in D. quadramaculatus and L. marmoratus. Atavism and selection pressures for paedomorphosis, terrestriality, and/or miniaturization may be involved in cloacal variation among female desmognathines.

The amphibian order Urodela (Caudata) consists of three extant suborders split into nine families, some 62 genera, and approximately 360 species (Duell- man & Trueb, 1986). Members of two suborders, Sirenoidea (3 species) and Cryptobranchoidea (35 species) undergo external fertilization of eggs, the presumed ancestral state for salamanders, and possess relatively unspecialized cloacae containing no (Sirenoidea) or one (Cryptobranchoidea) type of accessory sex gland (Sever, 1987). The remaining suborder, Salamandroidea, contains those families of salamanders in which fertilization occurs internally after the sperm-containing cap of a spermatophore produced by the male is maneuvered into the cloaca of the female where sperm storage organs, the spermathecae, occur. The spermathecae, at least in oviparous species, hold sperm until the eggs pass through the cloaca during oviposition, thereby allowing temporal and spatial separation between mating and oviposition. In addition to spermathecae, other cloacal glands, called ventral glands and dorsal glands, have been described in females of various salamandroid genera (Sever, 1987). The function of these glands is largely unknown, although Sever (1988) suggested that the ventral glands secrete a mating pheromone. Within the Salamandroidea, the Plethodontidae is the largest family of sal-

1 This work was supported by National Science Foundation Grant BSR-8715341 to D. M. Sever.

TRANS. AM. MICROSC.Soc., 109(2): 193-204. 1990. ? Copyright, 1990, by the American Microscopical Society, Inc.

This content downloaded from 147.174.85.132 on Tue, 30 Jun 2015 16:08:50 UTC All use subject to JSTOR Terms and Conditions 194 TRANS.AM. MICROSC.SOC. amanders with 27 genera and about 220 species, and this family is considered phylogenetically the most recently derived and specialized of the Caudata (see Duellman & Trueb, 1986). The Plethodontidae contains two subfamilies, Des- mognathinae and Plethodontinae (see Wake, 1966). Desmognathinae consists of three genera and 13 species in the eastern United States with greatest diversity occurring in the presumed ancestral region (southern Appalachians) and adap- tive zone (mountain brooks) for the family. The male cloacal anatomy for these species was described by Sever (1983), but for female desmognathines, reports exist only for Desmognathus fuscus (see Kingsbury, 1895) and D. ochrophaeus (see Noble & Pope, 1929; Sever & Houck, 1985). These investigators reported that females examined by them possessed only one type of accessory sex gland in the cloaca, spermathecae. The apparent lack of ventral glands in female desmognathines was called a secondary loss by Sever (1987) who considered ventral glands symplesiomorphic for salamanders. One of us (S.E.T.), while conducting a study of the reproductive cycle of the desmognathine Desmognathus brimleyorum, noted the presence of ventral glands and dorsal glands in females. This led to the present study, in which we examined specimens of all recognized species of desmognathines to determine how prevalent the occurrence of ventral and dorsal glands are in the subfamily. The types of glands present may have value in elucidating the phylogeny of desmognathine salamanders.

MATERIALS AND METHODS Specimens were preserved in neutral-buffered 10% formalin and stored in 60% isopropanol or 70% ethanol. Snout-vent length (SVL) was measured from the tip of the snout to the posterior end of the vent to the nearest 0.1 mm. Cloacae were excised, rinsed in water, dehydrated in a graded series of ethanol, cleared with Histosol (National Diagnostics, Inc., Somerville, New Jersey), and embedded in paraffin for serial sectioning at 10 ,um. Sections were affixed to albuminized slides and stained with: hematoxylin-eosin; Mallory's triple stain (connective tissue); alcian blue 8GX at pH 2.5 counterstained with periodic acid and Schiff's reagent (PAS) (neutral and acidic mucosubstances); or the ninhydrin Schiff reaction counterstained with fast green FCF (proteins). Stain- ing procedures followed Humason (1979) and Sheehan & Hrapchak (1980). Three-dimensional reconstructions of cloacae of all species were performed using PC3D software (Jandel Scientific, Corte Madera, California) and a Jandel digitizing tablet with a Zenith ZF-248 microcomputer. Using specimens sec- tioned transversely, every fourth section was recorded for image reconstruction. During reconstructions, the cloacae were stretched 3 times in the anterior- posterior direction so that actual cloacal conformation was represented. The image for each section through the spermathecae and other cloacal glands was displayed three times so that gaps between digitized sections were closed. Finally, only alternate sections through the cloacal walls were displayed, and, except for Phaeognathus, the cloacal walls were made "transparent" so that underlying structures were visible. At least two individuals of each species were examined. Voucher specimens

This content downloaded from 147.174.85.132 on Tue, 30 Jun 2015 16:08:50 UTC All use subject to JSTOR Terms and Conditions VOL. 109, NO. 2, APRIL 1990 195 are in The University of Michigan Museum of Zoology (UMMZ), Auburn University Museum (AUM), or retained by S.E.T. (SET). Species, date collected, SVL, and localities are as follows: Desmognathus aeneus, 16 July 1972, SVL unknown (UMMZ 187396), Graham County, North Carolina, 21 October 1982, 24.6 mm SVL (UMMZ 187397), Monroe County, Tennessee; D. auriculatus, 24 October 1982, 45.9 mm SVL (UMMZ 187399), York County, South Carolina, 25 October 1982,40.3 mm SVL (UMMZ 187398), Hoak County, North Carolina; D. brimleyorum, 10 April 1974, 69.6 mm SVL (UMMZ 187400), Montgomery County, Arkansas, 11 July 1980, 68.0 mm SVL (SET 3478) and 69.0 mm SVL (SET 3466), 15 August 1980, 69 mm SVL (SET 3553), and 15 March 1984, 75.0 mm SVL (SET 4247), Polk County, Arkansas; D. fuscus, 11 July 1970, 48.8 mm SVL (UMMZ 187402), Coshocton County, Ohio, 27 October 1983, 55.0 mm SVL (UMMZ 187401), Jackson County, Alabama; D. imitator, 23 October 1977, 38.0 mm SVL (UMMZ 187403), 44.6 mm SVL (UMMZ 187404), Sevier County, Tennessee; D. monticola, 3 October 1970,62.7 mm SVL (UMMZ 187405), Monongalia County, West Virginia, 17 March 1982, 68.8 mm SVL (UMMZ 187407), Graham County, North Carolina; D. ochrophaeus, 25 April 1970, 37.7 mm SVL (UMMZ 187408), Monongalia County, West Virginia, 7 August 1982,42.1 mm SVL (UMMZ 187409), Graham County, North Carolina, 18 March 1979, 41.7 mm SVL (UMMZ 187410), Blount County, Tennessee; D. quadramaculatus, 18 March 1982, 75.7 mm SVL (UMMZ 187411), Macon County, North Carolina, 21 October 1982, 83.8 mm SVL (UMMZ 187412), Monroe County, Tennessee; D. santeetlah, 20 March 1979, 42.0 mm SVL (UMMZ 187415), 42.7 mm SVL (UMMZ 187414), and 43.7 mm SVL (UMMZ 187413), Graham County, Tennessee; D. welteri, 18 October 1981, 71.0 mm SVL (UMMZ 187416), Wolf County, Kentucky, 19 October 1981, 65 mm SVL (UMMZ 187417), Harlan County, Kentucky; D. wrighti, 24 July 1973, SVL unknown (UMMZ 187418), Jackson County, North Carolina, 11 August 1982, 28.4 mm SVL (UMMZ 187420) and 29.0 mm SVL (UMMZ 187419), Avery County, North Carolina; Leurognathus marmoratus, 28 July 1973, 71.1 mm SVL (UMMZ 187421), Macon County, North Carolina, 24 October 1982, 70.5 mm SVL (UMMZ 187422), Haywood County, North Carolina; Phaeognathus hubrichti, 11 February 1967, 113 mm SVL (AUM 4514), Butler County, Al- abama, 11 October 1968, 102 mm SVL (AUM 11224), Covington County, Alabama, 7 November 1968, 113 mm SVL (AUM 11115) and 1 February 1969, 118 mm SVL (AUM 11430), Monroe County, Alabama, 15 March 1969, 110 mm SVL (AUM 11491), Crenshaw County, Alabama.

RESULTS The cloaca begins anteriorly where the urogenital ducts and urinary bladder join the posterior end of the intestine (Sever, 1978). Posterior to this, the cloaca typically consists of a closed cavity, the cloacal tube, and an open cavity dorsal to the cloacal orifice, the cloacal chamber. Figures 1-4 illustrate cloacae of Desmognathus fuscus, D. brimleyorum, Leurognathus marmoratus, and Phaeognathus hubrichti as reconstructed from transverse serial sections to show the diversity of cloacal structure in desmog-

This content downloaded from 147.174.85.132 on Tue, 30 Jun 2015 16:08:50 UTC All use subject to JSTOR Terms and Conditions 196 TRANS. AM. MICROSC. SOC.

Cs Sp

n0 ww\m] r AAA 9 Io %No -, - I i ^JM 2

I '2 211A3 ....-..-.---. 4 FIGS. 1-4. Three-dimensional reconstructions of the cloacae of female desmognathine salamanders to show the diversity of structure. Right lateral views rotated 25? clockwise (Figs. 1-3) or counterclockwise (Fig. 4). For other details of image reconstruction, see text. Fig. 1. Desmognathus fuscus (UMMZ 187401). Fig. 2. D. brimleyorum (UMMZ 187400). Fig. 3. Leurognathus marmoratus (UMMZ 187421). Fig. 4. Phaeognathus hubrichti (AUM 11430). Cc, cloacal chamber; Cr, recess of the cloacal chamber; Cs, common tube of the spermathecae; Ct, cloacal tube; Dg, dorsal glands; Ov, oviducts; Sp, spermathecae; Vg, ventral glands. nathines. The posterior one-half of the cloacal chamber is not shown. Figs. 1- 3 are right lateral views with the anterior end rotated 250 clockwise and the cloacal walls transparent. Fig. 4 illustrating the cloaca of P. hubrichti is a lateral view with the posterior end rotated 250 counterclockwise; this provides a better

This content downloaded from 147.174.85.132 on Tue, 30 Jun 2015 16:08:50 UTC All use subject to JSTOR Terms and Conditions VOL. 109, NO. 2, APRIL 1990 197 view of cloacal relationships for this species. Also in Fig. 4, only the right half of the cloacal walls and oviducts is displayed, and this is not transparent; otherwise, the complexity of the cloacal walls would obscure the arrangement of cloacal glands. Figs. 5-12 show representative transverse sections through the species illustrated by Figs. 1-4. In Desmognathus quadramaculatus and Leurognathus marmoratus, a cloacal tube is wanting (Fig. 3), and the urogenital ducts empty directly into the anterior end of the cloacal chamber. In P. hubrichti, anterior, paired recesses of the cloacal chamber extend dorsally to the cloacal tube and the distal ends of the oviducts pass into these (Figs. 4, 11). In the remaining species of Des- mognathus, the cloacal tube constitutes 10-30% of the total cloacal length. In all species, spermathecae are evident in the connective tissue dorsal to the anterior portions of the cloaca. Except for P. hubrichti, spermathecal acini pass into a common tube that opens into the roof of the cloaca on a medial fold that is formed posterior to the junction of the oviducts with the cloaca. In all species of Desmognathus except D. quadramaculatus, the common tube of the spermatheca opens on the medial fold at the posterior end of the cloacal tube, and spermathecal acini extend posteriorly (Figs. 1, 2). The medial fold continues as a distinct ridge into the anterior one-half of the cloacal chamber (Figs. 6, 8). Lateral to the medial fold, the walls of the cloacal tube and lateral walls of the anterior one-half of the cloacal chamber consist of 4-8 pairs of folds (Figs. 1, 2, 5, 7). The medial fold and the walls of the cloacal tube and dorsal one-half of the cloacal chamber are lined with simple, columnar mucosa that is continuous with that of the posterior intestine. The mucosa is glandular and apical ends of the epithelial cells give positive reactions with PAS and alcian blue at pH 2.5, indicating sulfated mucosubstances. The epithelium lacks cilia throughout the cloaca. In the posterior one-half of the cloacal chamber, the medial and lateral folds terminate coincidently with a gradual dorso-ventral shortening of the cavity. Posterior to these folds, stratified, aglandular epidermis continuous with that of the skin surrounding the cloacal orifice lines the cloacal chamber. In D. quadramaculatus and L. marmoratus, which lack a distinct cloacal tube, the common tube of the spermathecae passes into the medial fold just posterior to the junction of the oviducts in the anteriormost end of the cloacal chamber (Figs. 3, 9). Otherwise, relationships are much like other species of Desmognathus. In P. hubrichti, the spermathecal acini extend anteriorly from a common tube that passes into the cloacal recess dorsal to the posterior end of the cloacal tube and medial to the distal ends of the oviducts (Figs. 4, 11). The common tube of P. hubrichti, therefore, is horizontally directed and does not pass into a medial fold. In P. hubrichti, a medial fold appears in the anterior portion of the cloacal chamber caudad to the spermathecae. The spermathecae of all species are similar in their cytological features. The spermathecae of nearly all specimens examined contained spermatozoa, although in some individuals the amount was scant. In specimens containing spermatozoa, the common tube and spermathecae are lined with unciliated,

This content downloaded from 147.174.85.132 on Tue, 30 Jun 2015 16:08:50 UTC All use subject to JSTOR Terms and Conditions 198 TRANS.AM. MICROSC.SOC.

FIGS.5-8. Transverse sections throukh the cloacae of Desmognathus fuscus (Figs. 5, 6) and D. brimleyorum (Figs. 7, 8) illustrated in Figs. 1 and 2, respectively. Figs. 5, 7 show sections through the cloacal tube and Figs. 6, 8 show sections through the cloacal chamber. Sections stained with

This content downloaded from 147.174.85.132 on Tue, 30 Jun 2015 16:08:50 UTC All use subject to JSTOR Terms and Conditions VOL. 109, NO. 2, APRIL 1990 199

columnar epithelium that reacts positively with PAS and alcian blue at pH 2.5. The spermathecal epithelium in individuals lacking sperm is cuboidal and gives no reaction to diagnostic stains and treatments. The spermathecae have an outer fibrous/muscular capsule that in other species has been shown to represent myoepithelial cells (Dent, 1970; Pool & Hoage, 1973), although we are unable to confirm myoepithelium in our specimens using the techniques outlined here. The spermathecae are structurally simple branched acinar glands (Copen- haver et al., 1978). The proximal end of the common tube widens and lateral acini of interconnected chambers irregularly evaginate from the central cavity. In glands containing much spermatozoa, spermatozoa form whorls that fill the lumina. Some of these spermatozoa have their heads in contact with the spermathecal epithelium, but most spermatozoa are free of the epithelium (cf. Sever & Houck, 1985). In glands containing scant spermatozoa, the spermatozoa are scattered in the lumina and are not in contact with the epithelium. Individuals of most species also possess additional clusters of simple, tubular exocrine glands in the cloaca. Following Sever (1986), these glands are called dorsal glands and ventral glands on the basis of their position, although the two types are similar cytologically. All specimens of D. aeneus and D. wrighti examined lack cloacal glands other than spermathecae, and such glands also are absent in one D. fuscus (UMMZ 187402) and two D. ochrophaeus (UMMZ 187408-9). Other D. fuscus (UMMZ 187401) and D. ochrophaeus (UMMZ 187410) possess dorsal glands. Dorsal glands may occur in the medial fold anterior or lateral to the common tube of the spermathecae and/or posterior to the common tube in the medial fold, or just caudad to the medial fold in the cloacal chamber. The number of dorsal glands is 2-6 in the anterior group and 4-10 in the posterior group. In D. auriculatus, D. fuscus, D. imitator, D. quadramaculatus, and D. santeetlah, only the anterior group of dorsal glands occurs, and in L. marmoratus and P. hubrichti, only the posterior group is found (Figs. 1, 3, 4, 10, 12). Both anterior and posterior groups are present in the D. ochrophaeus with dorsal glands and in D. brimleyorum, D. monticola, and D. welteri (Figs. 2, 7, 8). Ventral glands are present in D. brimleyorum, D. monticola, D. welteri, L. marmoratus, and P. hubrichti, in all of which 6-10 pairs occur, and in D. imitator, in which 4-6 pairs are found (Figs. 2, 3, 4, 7). A group of 6-8 pairs of ventral glands occurs in one D. quadramaculatus (UMMZ 187412) but are lacking in the other specimen of this species examined (UMMZ 187411). In L. marmoratus, ventral glands occur sporadically along the inferior lateral walls of the cloacal chamber (Fig. 3). In the other species, ventral glands are found in the submucosal connective tissue lateral and ventral to the cloacal tube and anterior cloacal chamber (Figs. 2, 4, 7). These glands secrete onto the surface of the folds at the anterior end of the cloacal chamber. Distal ends of the ventral glands pass anteriorly.

hematoxylin and eosin. Scale bar represents 200 ,um;scale same for Figs. 5-8. Cc, cloacal chamber; Cs, common tube of the spermathecae; Ct, cloacal tube; Dg, dorsal glands; Mf, medial fold; Sp, spermathecae; Sz, spermatozoa; Vg, ventral glands.

This content downloaded from 147.174.85.132 on Tue, 30 Jun 2015 16:08:50 UTC All use subject to JSTOR Terms and Conditions 200 TRANS.AM. MICROSC.SOC.

_'I 1 OV 114 * \ V 12

FIGS.9-12. Transverse sections through the cloacae of Leurognathus marmoratus (Figs. 9, 10) and Phaeognathus hubrichti (Figs. 11, 12). The micrograph of L. marmoratus is of UMMZ 187421 and that of P. hubrichti is the same as that shown in Fig. 4. Figs. 9, 11 show sections through the

This content downloaded from 147.174.85.132 on Tue, 30 Jun 2015 16:08:50 UTC All use subject to JSTOR Terms and Conditions VOL. 109, NO. 2, APRIL1990 201

Both dorsal and ventral glands are rudimentary in appearance. They possess narrow lumina, and the epithelium is squamous or cuboidal with the nucleus filling most of the cells. Rarely does a secretory product occur in the lumina, although apices of the epithelial cells often give a positive reaction with alcian blue at pH 2.5.

DISCUSSION The plethodontid subfamily Plethodontinae consists of three tribes, Hemi- dactyliini, Plethodontini, and Bolitoglossini (see Wake, 1966). The hemidactyliines are considered to be closest in their morphology to the presumed plethodontid basic stock. The only plethodontines in which female cloacal anatomy has been examined are Plethodon cinereus, P. dorsalis, and P. glutinosus (see Kingsbury, 1895; Sever, 1978; Trauth, 1984), and the only glands present in their cloacae are spermathecae. No bolitoglossine cloacae have been described. Nineteen of the 20 species of hemidactyliines have been examined, and all possess ventral glands in addition to spermathecae (Sever, 1985, 1986, 1987; Trauth, 1983). The ventral glands of hemidactyliines, in contrast to those of the desmognathines, consist of large clusters of tubules that hypertrophy seasonally. Sever (1988), studying Eurycea cirrigera, demonstrated that the peak of the secretory cycle of female ventral glands correlated with a preoviposi- tory mating season, and suggested that the glands secrete a mating pheromone. Ventral glands also are known from all other families of salamanders except Sirenidae (Sever, 1987, 1988). Sever (1987) concluded that ventral glands prob- ably are symplesiomorphic for salamanders, and their absence in some species is secondary. Female dorsal glands previously were known only from some species in various salamandroid families Salamandridae and Ambystomatidae, and from the hemidactyliine genera in the Plethodontidae (see Sever, 1986, 1987). Except for the salamandrid genera Pachytriton (see Wahlert, 1953) and Pleurodeles (see LeMaitre-Lutz, 1968), the female dorsal gland has been described as rudimentary or vestigial, and these conditions apply to the dorsal glands of female desmognathines. Because dorsal and ventral glands are known in female hemidactyliines, the discovery of these glands in desmognathines does not help to clarify relationships between plethodontids and other spermatophore-producing families. The presence of these glands in both subfamilies of plethodontids, however, does have implications for phylogeny within the Plethodontidae. The common ancestor of both clades must have possessed these glands, unless they are homoplastic in plethodontids, which seems unlikely based upon the anatomical similarity of the glands (Sever, 1986, 1987). Thus, our findings present further evidence of the divergence of the subfamilies Desmognathinae and Plethodontinae early anterior and Figs. 10, 12 show sections through the posterior cloacal chamber. Scale bar represents 200 ,im; scale same for Figs. 9-12. Cc, cloacal chamber; Cr, recess of the cloacal chamber; Cs, common tube of the spermathecae; Dg, dorsal glands; Mf, medial fold; Ov, oviducts; Sp, spermathecae.

This content downloaded from 147.174.85.132 on Tue, 30 Jun 2015 16:08:50 UTC All use subject to JSTOR Terms and Conditions 202 TRANS.AM. MICROSC.SOC. in the evolution of the Plethodontidae (see Wake, 1966). Further work is needed on the occurrence of dorsal and ventral glands among females in the plethodontid tribes Bolitoglossini and Plethodontini. The implications of our findings for resolving the phylogeny of desmognathines also must await further research on the group. Relationships among the various species are poorly known, and the alpha taxonomy in some groups has not been resolved (Karlin & Guttman, 1986; Shontz, 1968; Tilley, 1988). In a study of male cloacal anatomy, Sever (1983) found that the desmognathines fall into three groups, one containing Phaeognathus hubrichti, another containing Desmognathus quadramaculatus and Leurognathus marmoratus, and a final group containing the remaining species of Desmognathus (the "typical desmognathine pattern"). Male P. hubrichti possess the simplest, most reduced cloacal structure known for plethodontids, and this species lacks two types of glands and conformational features known from the cloacae of other male desmognathines (Sever, 1983). Female P. hubrichti differ from females of other desmognathines in several aspects of cloacal anatomy: (1) the spermathecae pass anteriorly (rather than posteriorly) from the common tube; (2) the spermathecae lie medially to the distal ends of the oviducts; (3) the common tube is horizontally oriented; and (4) the common tube passes into a recess of the cloacal chamber that lies dorsally to the cloacal tube. Wake (1966) believed that P. hubrichti is a relatively advanced, specialized species derived from a Desmognathus-Leurognathus stock at a relatively early date. Our results add evidence to the idea that P. hubrichti is quite isolated phyletically from other desmognathines. Whereas the "simple" male cloacal anatomy could be interpreted as retention of an ancestral state, the female cloacal anatomy is quite unlike that known for any female salamander (Sever, 1987), and, therefore, is a specialization. Male D. quadramaculatus and L. marmoratus differ from the typical pattern by lacking a distinct cloacal tube (Sever, 1983), and we found this true for the females as well. These species are the most aquatic of the desmognathines. The shortened cloaca may represent retention of aspects of ancestral larval morphology in these forms. If so, the effect of paedomorphosis on cloacal conformation, but not on other aspects of cloacal anatomy in these forms, indicates heterochrony (Gould, 1977). For the remaining species of Desmognathus, the cloacal glands are most developed in D. brimleyorum, D. monticola, and D. welteri, in which anterior and posterior dorsal glands and ventral glands occur along with the spermatheca. D. brimleyorum is a form restricted to the Ouachita Mountains, D. welteri is found only in southeastern Kentucky and the southwestern corner of Virginia, and D. monticola is found widely through the Appalachian highlands, including the range of D. welteri. All of these species are large (60-80 mm SVL) robust salamanders restricted to the vicinity of mountain streams, the presumed ancestral habitat of plethodontids. The occurrence of dorsal glands in these forms, in Phaeognathus, and in hemidactyliines (as discussed previously) indicates that possession of these glands is the ancestral condition of the Desmognathus-

This content downloaded from 147.174.85.132 on Tue, 30 Jun 2015 16:08:50 UTC All use subject to JSTOR Terms and Conditions VOL. 109, NO. 2, APRIL 1990 203

Leurognathus lineage. Loss of one or more of the gland clusters in some species, therefore, is secondary. In this regard, the absence of cloacal glands, other than spermathecae in D. wrighti and D. aeneus, is noteworthy. These species have restricted ranges in the southern Appalachian Mountains and are the smallest (25-30 mm SVL) species of Desmognathus. The loss of accessory cloacal glands may be related to the evolution of miniaturization in these forms (Hanken, 1982). D. aeneus and D. wrighti also are among the most terrestrial desmognathines. Thus, the loss of dorsal and ventral glands may have accompanied selection for terrestriality. Females of entirely terrestrial species in the genus Plethodon lack cloacal glands other than spermathecae (Sever, 1978; Trauth, 1984). The sporadic occurrence of one or more accessory cloacal glands in some species and/or individuals of some species, but not others of the same species, may represent the effects of natural selection on a continuum of populations that bridge the gap between the large aquatic species that have retained all of the glands (D. brimleyorum, D. monticola, D. welteri) and the small, terrestrial species in which accessory gland clusters are lost (D. aeneus, D. wrighti). Members of the D. fuscus-santeetlah-auriculatus complex and the D. ochrophaeus-imitator complex are somewhere between these extremes in body size, terrestriality, and number of female cloacal glands. Thus, selection pressures for paedomorphosis, terrestriality, and/or miniaturization may be involved in cloacal variation among female desmognathines. In addition, the presence of dorsal and ventral glands may be atavistic. Wake & Elias (1983) proposed that the occasional occurrence of the septomaxilla in some bolitoglossine salamanders was based upon reversal of an original pae- domorphic event. In all female desmognathines, the accessory cloacal glands seem rudimentary. We cannot imagine a role for their secretion in any reproductive activity as hypothesized for the large, seasonally hypertrophying ventral gland clusters found in hemidactyliines (Sever, 1988). Thus, we consider the dorsal and ventral glands to be vestigial structures of little functional importance in desmognathines. Finally, the diagrammatic representation of a midsagittal section through the cloaca of a female D. fuscus figured by Noble (1931) and later used by Duellman & Trueb (1986) is in error by showing a tongue-like extension of the dorsal cloacal wall posterior to the spermathecae with a recess of the cloacal chamber dorsal to this extension. A medial fold is a conspicuous structure of the anterior cloacal wall in species of Desmognathus and L. marmoratus, but no recess occurs dorsally to it.

LITERATURE CITED

COPENHAVER, W. M., KELLY,D. E. & WOOD, R. L. 1978. Bailey's Textbook of Histology, 17th ed. Williams and Wilkins Co., Baltimore. 800 pp. DENT, J. N. 1970. The ultrastructure of the spermatheca of the red spotted newt. J. Morphol., 132: 379-424. DUELLMAN,W. E. & TRUEB,L. 1986. Biology of Amphibians. McGraw-Hill, New York. 670 pp. GOULD,S. J. 1977. Ontogeny and Phylogeny. Belknap Press, Cambridge, Massachusetts. 501 pp.

This content downloaded from 147.174.85.132 on Tue, 30 Jun 2015 16:08:50 UTC All use subject to JSTOR Terms and Conditions 204 TRANS. AM. MICROSC. SOC.

HANKEN, J. 1982. Appendicular skeletal morphology in minute salamanders, genus Thorius (Amphibia, Plethodontidae): growth regulation, adult size determination, and natural variation. J. Morphol., 174: 57-77. HUMASON, G. L. 1979. Animal Tissue Techniques, 4th ed. W. H. Freeman, San Francisco. 661 pp. KARLIN, A. & GUTTMAN,S. I. 1986. Systematics and geographic isozyme variation in the plethodontid salamander Desmognathus fuscus (Rafinesque). Herpetologica, 42: 283-301. KINGSBURY, B. F. 1895. The spermatheca and methods of fertilization in some American newts and salamanders. Trans. Am. Microsc. Soc., 17: 261-304. LEMAITRE-LUTZ,F. 1968. Anatomie des glandes pelviennes de la femelle de Pleurodeles waltlii Michah: leur r6le de receptacle seminal. Ann. Embryol. Morphol., 1: 409-416. NOBLE, G. K. 1931. Biology of the Amphibia. McGraw-Hill, New York. 577 pp. NOBLE,G. K. & POPE,S. H. 1929. The modification of the cloaca and teeth of the adult salamander, Desmognathus, by testicular transplants and castration. J. Exp. Biol., 6: 399-411. POOL, T. B. & HOAGE, T. R. 1973. The ultrastructure of secretion in the spermatheca of the salamander, Manculus quadridigitatus (Holbrook). Tissue Cell Res., 5: 303-313. SEVER, D. M. 1978. Female cloacal anatomy of Plethodon cinereus and Plethodon dorsalis (Amphibia, Urodela, Plethodontidae). J. Herpetol., 12: 397-406. 1983. Cloacal anatomy of male salamanders in the plethodontid subfamily Desmognathinae. Herpetologica, 39: 16-27. 1985. Sexually dimorphic glands of Eurycea nana, Eurycea neotenes and Typhlomolge rath- buni (Amphibia: Plethodontidae). Herpetologica, 41: 71-84. 1986. Disparate sexual variation among Gyrinophilus, Pseudotriton and Stereochilus (Am- phibia: Plethodontidae). Herpetologica, 42: 301-323. 1987. Hemidactylium scutatum and the phylogeny of cloacal anatomy in female salamanders. Herpetologica, 43: 105-116. 1988. The ventral gland in female salamander Eurycea bislineata (Amphibia: Plethodontidae). Copeia, 1988: 572-579. SEVER, D. M. & HOUCK, L. D. 1985. Spermatophore formation in Desmognathus ochrophaeus. Copeia, 1985: 394-402. SHEEHAN, D. C. & HRAPCHAK, B. B. 1980. Theory and Practice of Histotechnology, 2nd ed. Battelle Press, Columbus, Ohio. 481 pp. SHONTZ, N. N. 1968. Electrophoretic patterns of proteins of salamanders of the genus Desmog- nathus (family Plethodontidae). Copeia, 1968: 683-692. TILLEY, S. G. 1988. Hybridization between two species of Desmognathus (Amphibia: Caudata: Plethodontidae) in the Great Smoky Mountains. Herpetol. Monogr., 2: 27-39. TRAUTH, S. E. 1983. Reproductive biology and spermathecal anatomy of the dwarf salamander (Eurycea quadridigitata) in Alabama. Herpetologica, 39: 9-15. 1984. Spermathecal anatomy and the onset of mating in the slimy salamander (Plethodon glutinosus) in Alabama. Herpetologica, 40: 314-321. WAHLERT, G. VON. 1953. Eileiter, Laich, und Kloake der Salamandriden. Zool. Jahrb., 73: 276- 324. WAKE, D. B. 1966. Comparative osteology and evolution of the lungless salamanders, family Plethodontidae. Mem. So. Calif. Acad. Sci., 4: 1-111. WAKE, D. B. & ELIAS, P. 1983. New genera and a new species of central American salamanders, with a review of the tropical genera (Amphibia, Caudata, Plethodontidae). Nat. Hist. Mus. Los Angeles Co., Contrib. Sci., 345: 1-19.

This content downloaded from 147.174.85.132 on Tue, 30 Jun 2015 16:08:50 UTC All use subject to JSTOR Terms and Conditions