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A naturally metamorphosed Tennessee cave salamander (Gyrinophilus palleucus)

A naturally metamorphosed Tennessee cave salamander (Gyrinophilus palleucus)
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  JOURN L OF  THE Tennessee  cademy  of  Science VOLUME  LXI  JANUARY  1986 JOURN L  OF THE  TENNESSEE C DEMY  OF  SCIENCE VOLUME  61,  NUMBER  1,  J NU RY ,  1986 N TUR LLY  MET MORPHOSED  TENNESSEE  C VE  S L M NDER GYRINOPHILUS PALLEUCUS) RON LD  A BR NDON Southern  Illinois  University Carbondale,  Illinois  62901 JEREMY  J COBS University  of Maryland College  Park, Maryland 20742 DDISON WYNN National Museum of Natural History Washington, D. C. 20560 and D VID  M SEVER Saint Mary s College Notre Dame, Indiana 46556 BSTR CT The  only known naturally  metamorphosed  Gyrinophilus palleucus  is described and compared to individuals of the species  that  have transformed in the laboratory, and to the only  other  individual of the species previously found transformed in  nature,  a specimen of  G. p. gulolineatus. The  osteology  of the naturally transformed  G. p. palleucus is  similar to  that  known for  other  postmetamorphic  Gyri- nophilus  except  that  it retains the  larval,  undivided condition of the premaxilla, although  parasphenoid  teeth  are well-formed.  This  is similar to  G. p. palleucus  that  transform in the laboratory. The naturally  metamorphosed  G. gulolineatus,  in  contrast,  has a divided premaxilla but lacks  parasphenoid teeth.  Our  data  further  support  specific recognition of  G. p. gulolineatus. INTRODUCTION Although individuals of  Gyrinophilus p. palleucus,  the Tennessee cave salamander, have readily  been  induced to undergo  metamorphic  change  in the laboratory  Blair,  1961;  Dent et al., 1955; Dent and  Kirby-Smith,  1963; Yeatman, 1967) and occasionally transform  spontaneously in  the laboratory (Dent and  Kirby-Smith,  1963), no transformed individuals of this subspecies have  been reported from  nature.  Within the species, only one such  postmeta morphic animal has  been reported,  a specimen of  G. p. gulolineatus  from Mud Flats Cave,  Knox  County, Tennessee (Simmons, 1976). Mud Flats Cave and Meade s Quarry Cave,  both near  Knoxville,  Tennessee, are the only  locali ties so far known where the troglobitic  G. palleucus  and its epigean congener  G. porphyriticus  occur sympatrically (Simmons, 1975). Because of the possibility his specimen may have  been  a hybrid  between  the two species (although Simmons concluded it was not a hybrid), confirmation that  occasional individuals of  G. palleucus  transform in other  caves where  G. porphyriticus  does  not occur helps clarify  the  status  of the  Knox  County specimen. This  note  reports  a transformed specimen of  G. p. pal- leucus  from Custard Hollow Cave,  Franklin  County,  Ten nessee.  Over the  past  30 years, ca. 60 additional individuals of  this species, all branchiate, have  been  collected at this locality, and no specimens of  G. porphyriticus  are known from the cave. RESULTS  AND  DISCUSSION The  transformed animal (Fig. 1,  USNM  FS 030391), a mature  male, 77 mm  snout-vent  length  SVL),  was  col lected June 26, 1983, along with  branchiate  individuals. It FIG 1.  Transformed adult male  Gyrinophilus p. palleucus USNM  FS 030391; 77 mm SVL) from Custard Hollow Cave,  Franklin  County, Tennessee.  2 JOURNAL  OF  THE  TENNESSEE ACADEMY  OF  SCIENCE was found hanging to the side of a rock  about  15 cm beneath the surface of water in a pool  about  50 cm  deep.  It was not found near the entrance, but  well  within  the cave where the branchiate  G. palleucus  were also found.  Aside from  being paler in coloration, yet mottled and spotted with  darker pigment on the back, it resembled the gaunt specimen illustrated by Simmons (1976, Fig. 1) and was likewise  extremely emaciated. When examined, stomach and intestines were found to be devoid of food. Testes and vasa deferentia were darkly pigmented,  indi cating maturity. One testis examined histologically was found to be undergoing spermatogenesis,  with  primary spermatocytes anteriorly and secondary spermatocytes and spermatids in the more swollen posterior portion. The tes tis  and vas deferens were devoid of mature spermatozoa. None of the  five  branchiate specimens  (39-81  mm  SVL) collected in the cave at the same time had mature reproductive tracts. FIG.  2  Radiographs  of  skulls  of  Gyrinophilus  p. palleucus from  Custard  Hollow  Cave,  Franklin  County, Tennessee. A)  Branchiate individual, 80 mm SVL; B) The naturally transformed  adult male, 77 mm SVL. Abbreviations are: PM  = premaxilla; PP ~ palatopterygoid; PS = parasphe-noid; and PV   prevomerine. Under radiography (Fig. 2), the specimen was seen to have 19 trunk vertebrae, and 11 intact and 13 regenerated caudal vertebrae. It had 58/59 parasphenoid teeth, 11/10 prevomerine teeth, 25/26  maxillary  teeth, and 15 premaxil- lary  teeth. The dentiferous ramus of the premaxilla was not subdivided but was thinned in the center. Septomaxil- lary  bones  were present. The palatopterygoid appeared fully  transformed,  with  the pterygoid portion greatly reduced and reconstructed, and the palatine portion gone. The  prevomer was reconstructed, had a well-formed choa nal  notch, and appeared nearly  fully  transformed except that  the dentigerous portion was not aligned transversely as it is in most postmetamorphic  G. porphyriticus  Bran don, 1966, Fig. 8). The  hyobranchial apparatus was  fully  transformed, and the nasolabial grooves were present. The  tongue  was not completely boletoid; it was undercut to the same  degree  as in  adult  Typhlotriion spelaeus,  with  a thin frenulum left in front. Well-formed eyelids completely covered the recessed eyes,  which  were  about  1.3 mm in diameter or 0.017  SVL as is  typical  of this species (Besharse and Brandon,  1973). The labial  folds and  tail  fin were completely reduced although the  tail  was  still  compressed. The  transformed specimen from Custard  Hollow Cave had reduced numbers of prevomerine (21) and premaxil- lary  (15)  teeth  compared  with  branchiate animals, and many parasphenoid  teeth  were present, whereas in  Sim mons specimen of  G. p. gulolineatus,  numbers of prevomerine and premaxillary  teeth  remained high (76 and 25 respectively)  and no parasphenoid  teeth  had formed (Simmons, 1975).  Brandon  (1971)  reported 27-35 prevomerine  teeth  and 21-30 premaxillary  teeth  in branchiate  G. palleucus  36-104 mm  SVL,  with  little ontogenetic increase in  number. The  transformed Custard  Hollow Cave  specimen is more meaningfully compared  with  those  obtained in the laboratory by Dent and  Kirby-Smith  (1963)  and Yeatman  (1967) because they are all  G. p. palleucus,  and are all from nearby caves in the same  hill.  Simmons specimen,  which has the divided, transformed condition of the  Gyrinophilus premaxillary  bone  and no parasphenoid teeth, is from a population identifiable as  G. p. gulolineatus,  a distinctive form  that  reaches a larger size (Brandon,  1967).  In osteology, the Custard  Hollow Cave  specimen resembles  Yeat- man s  (1967)  description and illustration of an animal three  years beyond the beginning of metamorphosis, and is clearly  beyond the  degree  of metamorphosis shown by his animal  nine months after the beginning of metamorphosis. In  retaining the undivided,  larval  dentiferous ramus of the premaxilla,  the transformed Custard  Hollow Cave  specimen resembles  G. p. palleucus  that  have transformed in the laboratory, but differs from Simmons transformed specimen of  G. p. gulolineatus.  This  difference and others noted by Brandon  (1965)  may be taken as evidence  that  G. p.  gulolineatus  should be considered a  separate  species, one possibility Simmons  (1976)  considered. ACKNOWLEDGMENTS Fieldwork  was supported in part by NSF grant BRS-8117983 to R. Highton. LITERATURE CITED Besharse,  J. C. and R. A.  Brandon.  1973. Optoniotor response and eye structure  of the troglobitic salamander  Gvrinophilus palleucus American Midland  Naturalist 89:463-467. Blair A. P. 1961. Metamorphosis of  Pseudotriton palleucus  with iodine. Copeia  1961:499. Brandon,  R. A. 1965. A new  race  of the neotenic salamander  Gvrinophilus palleucus Copeia  1965:346-352. 1966. Systematics of the salamander genus  Gyrinophilus Illinois Biological Monographs 35:1-86. 1967.  Gyrinophilus palleucus Cat.  Amer. Amphib. Rept:  32. 1971.  North  American  troglobitic salamanders: some aspects of modification in cave habitats, with special reference to  Gyrinophilus pal- leucus National Speleol. Soc.  Bull.  33:1-21. Dent, J. N. and J. S.  Kirby-Smith.  1963. Metamorphic physiology and morphology of the cave salamander  Gvrinophilus palleucus Copeia 1963:119-130. and D. L.  Craig.  1955. Induction of metamorphosis in Gyrinophilus  palleucus Anatomical Rec. 121:429. Simmons, D. D. 1975. The evolutionary ecology of  Gyrinophilus palleucus Master s thesis. University of  Florida. 1976. A  naturally  metamorphosed  Gyrinophilus palleucus (Amphibia, Urodela,  Plethodontidae). J. Herpetoiogy 10:255-257. Yeatman.  H. C. 1967.  Artificially  metamorphosed neotenic cave  salamanders.  J. Tennessee  Acad.  Sci. 42:16-22.
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