Hamlett, Butch E.

Strecker, Andy G.

Trauth, Stanley E.

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Journal of the Arkansas Academy of ScienceVolume 52 Article 211998Caudal Courtship Glands in the Cave Salamander,Eurycea lucifuga (Caudata: Plethodontidae)Butch E. HamlettArkansas State UniversityAndy G. StreckerArkansas State UniversityStanley E. TrauthArkansas State UniversityFollow this and additional works at: http://scholarworks.uark.edu/jaasPart of the Terrestrial and Aquatic Ecology Commons, and the Zoology CommonsThis article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able toread, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking priorpermission from the publisher or the author.This General Note is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the ArkansasAcademy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu.Recommended CitationHamlett, Butch E.; Strecker, Andy G.; and Trauth, Stanley E. (1998) "Caudal Courtship Glands in the Cave Salamander, Eurycealucifuga (Caudata: Plethodontidae)," Journal of the Arkansas Academy of Science: Vol. 52 , Article 21.Available at: http://scholarworks.uark.edu/jaas/vol52/iss1/21124GENERAL NOTESCaudal Courtship Glands in the Cave Salamander, Eurycea lucifuga(Caudata: Plethodontidae)Butch E. Hamlctt, Andy G. Strecker, and Stanley E. TrauthDepartment of Biological SciencesArkansas State UniversityState University, AR 72467Noble (1929) first reported courtship glands in the tailbase of a plethodontid salamander, Eurycea bislineata. Todate, these sexually dimorphic caudal glands have beendemonstrated histologically only for Desmognathus (Noble,1931), Eurycea (Noble, 1929; Sever, 1989; Trauth et al.,1993), and Plethodon cinereus (see Houck and Sever, 1994).The term "hedonic gland" was used in previous research(Gadow, 1887; Noble, 1927, 1929, 1931; Rogoff, 1927) todescribe a cluster of glands that produced courtshippheromones. Because there was no evidence that the hedo-nic glands were indeed pleasure giving as the term implied,Arnold (1977) suggested the use of the term "courtshipgland." Houck and Sever (1994) adopted the term courtshipgland, and we follow their usage when referring tomale sex-ually dimorphic glands within the skin of the tail base.Caudal courtship glands are located on the dorsal baseof the male's tail and hypertrophy during the breeding sea-son; they presumably deliver secretions directly to thefemale during courtship (Sever, 1989). During the "tailstrad-dling" walk females place their snouts on the male's rumpdirectly over the caudal glands (Arnold, 1977). Caudalcourtship pheromones presumably increase female recep-tivity, thus making her more likely to become inseminatedby that male (Houck and Sever, 1994).Little is known about the reproductive biology of thecave salamander {Eurycea lucifuga) in Arkansas. Trauth et al.(1990) reported that females undergo vitellogenesis fromFebruary to August; however, no investigation on the breed-ing cycle and courtship activity of Eurycea lucifuga inArkansas animals has, thus far, been published. In the fol-lowingpaper, we provide the first histological description ofcaudal courtship glands of the male cave salamander,Eurycea lucifuga. Our specific objectives were to: 1) docu-ment the structure of caudal courtship glands using lightmicroscopy and 2) compare the morphology and secretionsof these glands with similar glands previously reported inother Eurycea.Thirty-eight adult male cave salamanders (45-61 mm insnout-vent length [SVL], x = 55.9 mm) were used in thisstudy. The animals were taken from the Arkansas StateUniversity Museum ofZoology (ASUMZ) and from the per-sonal collection of S. E. Trauth (SET). Specimens were col-lected from caves in the following counties of Arkansas:Fulton, Independence, Izard, and Stone. Collection dateswere from December 1977 toJuly 1997. The visible glandu-lar hump on the mid-dorsal region of the tail was measuredand removed; in addition, an equivalent region of skin wasexcised from animals that did not possess these protuber-ances. The tissue samples were prepared for lightmicroscopy using histological techniques outlined byHumason (1979); briefly, these steps were as follows: 1)dehydration in a graded series of ethanol, 2) clearing inxylene, and 3) embedding in paraffin. The tissue sampleswere oriented in the paraffin so that transverse or frontalsections could be obtained in a complete series. The tissuesamples were cut at 8 |im using a rotary microtome. Fourstaining procedures were used and are as follows: hema-toxylin-eosin (H&E) for general cytology, Pollak (Pollak)trichrome for connective tissues and mucosubstances, alcianblue 8GX at pH 2.8 for sulfated glycosaminoglycans, andperiodic acid-Schiff's reagent (PAS) for general carbohy-drates. These stains were alternately used on sequentialgroups of four slides. Glands were measured using a cali-brated ocular micrometer and reported in (im; glandularvolumes were derived using the formula for the volume of acylinder.Caudal courtship glands found inEurycea lucifuga do notshow a high degree of morphological variation. The glandstend to be either round or oblong in the pre-secretory stage(Fig. 1A), secretory stage (Fig. 2A,B, and C), and post-secre-tory stage (Fig 2D). The caudal courtships glands residedeep within the dermis and lie superficial to a layer of adi-pose tissue. The entire, elevated glandular hump rangedfrom 5.02 —11.9 mm in length (x= 7.69 mm).The epithelial lining of caudal courtship glands iscolumnar and variable in thickness (x = 60.2 ±5.2 (im,range, 29.2 - 99.3, n = 30) inrelation to secretory activity.These glands can be distinguished from other glands (name-ly,mucous and granular glands) by their size, staining prop-erties, and secretions. Caudal courtship glands are usuallygreater in width (x = 168.2 urn;range, 46.2 - 365.7, n= 130)and height (x= 190.1 um; range, 42.0 - 439.0; n =130) thanJournal of the Arkansas Academy of Science, Vol. 52, 1998124Journal of the Arkansas Academy of Science, Vol. 52 [1998], Art. 21Published by Arkansas Academy of Science, 1998125Caudal Courtship Glands in the Cave Salamander, Eurycea lucifuga (Caudata: Plethodontidae)Fig. 1. Photomicrographs of sagittal sections through the mid-dorsal region of the taildirectly above and posterior to the ventinEurycea lucifuga illustrating the caudal courtship glands and their relationship to other epidermal glanda. A.Section of maleskin (ASUMZ 20882) stained with H&E showing adipose tissue (A), mucous glands (MG), granular glands (GG), caudalcourtship glands (CCG), a thin epidermis (E), and the dorsal musculature (M). Notice the relationship in size of the caudalcourtship glands to the mucous and granular glands (specimen collected in February) before onset of the breeding season. B-D. Skin (ASUMZ 8147, 13966, SET 3841, respectively) stained with Pollak stain illustrating the relative increase in volume ofthe caudal courtship glands compared to other glands through the breeding season. Abbreviations the same as inA.Line inBthe same for C and D.either granular glands (width: x = 132.4 (im; range, 96.8 -161.5; n = 19; height: x = 98.3 urn; range, 76.9 - 126.9, n =19) or mucous glands (width: x = 64.3, urn; range, 38.5 -107.7; n= 17; height: x= 48.2 |im; range, 19.2 - 103.8; n =(). Inaddition, granular and mucous glands are mostly cir-ilar (Fig. 1A and B), whereas the caudal courtship glandse always barrel-like in shape (Fig. IB and C).(Seasonal variation was observed in the secretory activi-of caudal courtship glands of Eurycea lucifuga in Arkansasig. 3). In specimens collected from October to earlyMarch caudal courtship glands were in a regressed statewith most having little or no secretions. In contrast, caudalcourtship glands examined from May-August possessedlarge amounts of secretory material and had greatlyincreased in size; the largest glandular volumes wereobserved inJuly.The staining properties of the glandular secretions aresimilar to those that were reported in other Eurycea (Sever,1989; Trauth et al., 1993). Glandular gland secretions areeosinophilic using H&E and Pollak, but they show no reac-Journal of the Arkansas Academy of Science, Vol. 52, 1998125Journal of the Arkansas Academy of Science, Vol. 52 [1998], Art. 21http://scholarworks.uark.edu/jaas/vol52/iss1/21126Butch E. Hamlett, Andy G. Strecker, and Stanley E. TrauthFig. 2. A. Skin of male Eurycea lucijuga (ASUMZ 13966) stained with H&E illustrating the presence of a mucoprotein(eosinophilic) and columnar cells with basal nuclei; arrow indicates the duct opening. B-C. Skin (ASUMZ 13964; SET 3841,respectively) stained withPollak stain illustrating the presence of mucosubstances. The epithelial lining of the caudal courtshipgland appears lightpurple; the secretory column is a dark purple, except for portions that stain a dark brown to red. D.Skinof male (ASUMZ 14434) stained with PAS illustrating the regressed condition of the CCG following the breeding season(epithelial lining magenta in coloration). Line in Ais the same for B-D.tion with alcian blue, whereas the mucous glands contain afibrous secretion that stains positive with alcian blue andbasiophilic inH&E and Pollak. The staining characteristicsof the caudal courtship glands indicate that a mucoprotein isinvolved as the secretory product (Sever, 1989; Trauth et al.,1993). In E. luctfuga, the secretion of the caudal courtshipglands is PAS positive, alcian blue negative, and iseosinophilic using H&E. Staining with Pollak producedsome mixed results. In many cases the secretion stained alight to dark blue, but in others the secretion was a darkJournal of the Arkansas Academy of Science, Vol. 52, 1998126Journal of the Arkansas Academy of Science, Vol. 52 [1998], Art. 21Published by Arkansas Academy of Science, 1998127Caudal Courtship Glands in the Cave Salamander, Eurycea lucifuga (Caudata: Plethodontidae)Fig. 3. Seasonal variation in average glandular volume of caudal courtship glands from 28 Eurycea lucifuga. Volumes representvalues from five of the largest glands per specimen; the SVL's of specimens were as follows (linear order viewed inhistogram):Jan - 58; Mar - 55, 51, 51; May - 58, 56, 55; Jun - 54, 58, 54, 58, 58, 54; Jul - 60, 54, 60, 58, 57, 61; Aug -59, 55, 56; Oct -61, 48; Dec - 53, 50, and 52.brown or a shade ofred.KThe caudal courtship glands of E. lucifuga are similar inveral respects to those of other species of Eurycea (E. bis-lineata; E. cirrigera; E. junaluska; E. nana; E. wilderae) asreported by Sever (1985, 1989) and inE. multiplicata (Noble,1931). For instance, the round to barrel-like structure ofthese glands in the hypertrophied stage and the stainingproperties were consistent. The size of the caudal courtshipglands inE. lucifuga is larger than those found in the otherspecies of Eurycea, except for E. longicauda melanopleura(Trauth et al., 1993). E. lucifuga inthe present study averagedaround 8.2 mm greater in SVL compared to the E. I.melanopleura examined by Trauth et al. (1993).In summary, cave salamanders {Eurycea lucifuga) wereinvestigated for the presence of sexually dimorphic glandsin the tail base. These multicellular, acinar, exocrine glands(caudal courtship glands) lie deep within the dermis inmaleEurycea and produce a hypertrophied mid-dorsal area poste-rior to the vent. Caudal courtship glands can be distin-guished from other glands (namely, mucous and granular)by morphology as well as the staining properties of thesecretions. We found seasonal variation in the developmentof these glands; the glands exhibited their greatest volumein July at a time coinciding with ovarian enlargement infemales and were least in volume during the wintermonths.Acknowledgments. —We thank the Department ofBiological Sciences at Arkansas State University for provid-ing the facilities for competing this senior undergraduateresearch project. Constructive comments by two anony-mous reviewers greatly improved the final version of thismanuscript. Scientific collection permits were issued to S. E.Trauth under the authority of the Arkansas Game and FishCommission.Literature CitedArnold, S. J. 1977. The evolution of courtship behavior inNew World salamanders with some comments on OldWorld salarmanders. Pp. 141-183, In The reproductiveJournal of the Arkansas Academy of Science, Vol.52, 1998127Journal of the Arkansas Academy of Science, Vol. 52 [1998], Art. 21http://scholarworks.uark.edu/jaas/vol52/iss1/21E. Trauth52, 1998128Butch E. Hamlctt, Andy G. Strecker, and Stanleybiology of amphibians (D.H. Taylor and S.I. Guttman,eds.) Plenum Press, New York x+ 475 pp.Gadow, H. 1887. Remarks on the cloaca and copulatoryorgans of Amniota. Philos. Trans. 178(Ser. B): 5-37.Humason, G.L.1979. Animal tissue techniques, 4th ed. W.H. Freeman, San Francisco, ix + 661 pp.Houck, L.D. and D.M.Sever. 1994. Role of the skin inreproduction and behaviour. Pp. 351-381, InAmphibianbiology (H.Heatwole and G.T. Barthalmus, eds.) Vol.1.Surrey Beatty & Sons, Chipping Norton, NSW,Australia.Noble, G. K. 1927. The plethodontid salamanders, someaspects of their evolution Amer. Mus. Novitates 249:1-26.Noble, G. K. 1929. The relation of courtship to the sec-ondary sexual characters of the two-lined salamander,Eurycea bislineata (Green). Amer. Mus. Novitates 362:1-5.Noble, G. K. 1931. The hedonic glands of the plethodontidsalamanders and their relation to the sex hormones.Anat. Rec. 48:57-58.Rogoff,J. L.1927. The hedonic glands of Triturus viridescens:a structural and morphological study. Anat. Rec.34:132-133 (abst).Sever, D. M. 1985. Sexually dimorphic glands of Euryceanana, Eurycea neotenes and Typhlomolge rathbuni(Amphibia: Plethodontidae). Herpetologica 41:71-84.Sever, D.M.1989. Caudal hedonic glands in salamandersof the Eurycea bislineata complex (Amphibia:Plethodontidae). Herpetologica 45:322-329.Trauth, S. E., R. D. Smith, A. Cheng, and P. Daniel.1993. Caudal hedonic glands in the dark-sided sala-mander, Eurycea longicauda melanopleura (Urodela:Plethodontidae). Proc. Arkansas Acad. Sci. 47:151-153.Trauth, S. E.,R.L.Cox, B.P. Butterfield, D.A. Saugey,and W. E. Meshaka. 1990. Reproductive phenophasesand clutch characteristics of selected Arkansas amphib-ians. Proc. Arkansas Acad. Sci. 44:107-113.Journal of the Arkansas Academy of Science, Vol.128Journal of the Arkansas Academy of Science, Vol. 52 [1998], Art. 21Published by Arkansas Academy of Science, 1998

Caudal Courtship Glands in the Cave Salamander, Eurycea lucifuga (Caudata: Plethodontidae)

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Caudal Courtship Glands in the Cave Salamander, Eurycea lucifuga (Caudata: Plethodontidae)

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