Museum of Comparative Zoology Breviora 18

REVIORA jyi niseiim oi Lomparafive Zoology US ISSN Cambridge, Mass 0006-9698 Number 24 July 2008 513 DISTINGUISHING FEATURES OF THE SUB-SAHARAN FROG GENERA ARTHROLEPTIS AND PHRYNOBATRACHUS: A SHORT GUIDE FOR FIELD AND MUSEUM RESEARCHERS Breda M Zimkus Abstract Typically small distinguish between species of * and David Blackburn C body size and similar external anatomy have made it difficult for researchers to two distantly related, but often sympatric, African ranoid frog genera: Arthroleptis We define a suite of external morphological characters, extending beyond the traditionally used secondary sexual characteristics, that can be used to definitively distinguish (Arthroleptidae) and Phrynobatrachus (Phrynobatrachidae) between adult Arthroleptis and Phrynobatrachus Photographs comparing absence, presence, and variation of morphological characters are included for clarification Significant differences between body proportions (head width/snout-vent length) are also observed between these genera Although smaller species might be more difficult to identify, larger species (> 30 snout-vent length) oi Arthroleptis can be distinguished from Phrynobatrachus mm because of their relatively wider heads We intend guide for both this to serve as a heuristic field- and museum-based researchers Key words: Africa; Amphibia; Arthroleptidae: identification: INTRODUCTION Nearly every herpetologist is frogs." Many leaf litter brown anurans are small, generally drab in color, and morphologically similar, and this and identification in the field and in museum collections Within subSaharan Africa, two such genera, Arthroleptis Smith 1849 and Phrynobatrachus Giinther 1862, have been confused for more than a atic research familiar with the overwhelming diversity of "little Ranoidea: Phrynobatrachidae has hampered both system- century of (i.e., studies Laurent, Boulenger, 1882) of 1940, skeletal On the basis morphology 1941a b; Scott, 2005) (e.g and the results of molecular phylogenetic analy- Museum of Comparative Zoology, and Department of Organismic and Evolutionary Biology Harvard Univer1 ses (e.g., Bossuyt 2006; Roelants et at et a/., 2006; Frost et ah 2007) it is now very Cambridge Massachusetts 02138 U.S.A.: *Corresponding author E-mail: bzimkus) In this study, morphological useful in we examined characters a suite believed distinguishing between to of be adults of Anhroleptis and Phrynobatrachus The most BREVIORA Table External morphological characters useful for differentiating between Arthroleptis AND PhRYSOBATRACHCS Arthroleptis Character absent Tarsal tubercle Outer metatarsal tubercle Hourglass or triple diadem pattern on dorsum Chevron-shaped glands in scapular region Eyelid cornicle or spur Sexually mature males Elongate third finger Dermal No 513 digital spines Inguinal spines Nuptial excrescence (thickened pad of skin) on first finger Femoral gland Lateral vocal folds variable Phrynobatrachus present References DIAGNOSING ARTHROLEPTIS AND PHRYNOBATRACHUS 2008 African frogs, but the presence or combination particular characters can be useful in oi' between adult distinguishing and chus found in Expansion o\~ the manual and pedal digits Arthroleptis, terminal phalanx is Phrynobatra- o\' both genera, but circummarginal grooves are found only in some (Blackburn Phrynobatrachus species of 2005; poorly preserved specimens (Fig 2G); however, the presence of this character used accurately to some Finally, species can be Arthroleptis identify of Phrynobatrachus exhibit circummarginal grooves ual or pedal digit tips; in some on the manspecies, these furrows are found only on the longest digits In addition, the presence of circummarginal 2005; Fig 2E) Phrynobatrachus differs from grooves be Arthroleptis by the presence of pedal because of desiccation of preserved speci- many bing in Scott, web- species of the former (Schmidt Webbing ranges from absent or rudimentary in numerous smaller and Inger 1959) species such as P miliums, P parvulus, P and ukingensis to extensive in the majority of larger, rheophilic species P tris, and krefftii, such as P acutiros- versicolor (Fig 2C, P D) Five species of Phrynobatrachus, including P annulatus, P calcaratus, P cornutus, P taiensis, and P villiersi, spinelike dermal tubercle possess a single on the upper eyelid (Rodel, 2000) a character that can be used to distinguish Phrynobatrachus tis (Perret from Arthrolep- 1988), as well as other African anurans A number of external morphological characters vary both within and species in each genus, and between this variation is due to either natural variation within or between populations or the condition of preserved specimens Chevron-shaped glands in the scapular region of Phrynobatrachus and dorsal a triple Arthroleptis can diadem pattern in could mens However, if difficult determine to circummarginal grooves are present, this character can be used to Phrynobatrachus from Arthro- differentiate because leptis, not it necessarily genera is lacking in the latter, but from (Blackburn, other 2005; African frog Scott, 2005; The presence of male secondary sexual Fig 2E) characters can lead to the most straightfor- ward identifications of specimens as Arthro- leptis or Phrynobatrachus An elongate third found in many male Arthroleptis, as well as most species of Cardioglossa, the putative sister genus of Arthroleptis (Blackburn, in press; Fig 3A, B) This sexual dimorphism is not found in Phrynobatrachus or any other anurans Males of nearly all Arthroleptis species have dermal spines lining finger the is medial finger surface of the elongate third and are also sometimes found on the lateral, medial, or both second finger (Fig 3B) surfaces In some of the species, the presence of spines can vary seasonally both be used to identify (e.g., species of these genera (Scott, 2005; Stewart, some Schmidt and Inger, 1959) Males of species of Phrynobatrachus possess a However, these are not always prom- nuptial excrescence or thickened pad of skin members of a species or may be completely lacking in some species The size on the medial and dorsal surface of the first finger, which was hypothesized by Parker and shape of the chevron-shaped glands of Phrynobatrachus are quite variable and can originate and terminate in the scapular amplexus In 1974) inent in all region or instead extend almost the entire length of the body (Fig 2H) The median dorsal skin raphe of Arthroleptis can be a difficult character to visualize, especially in (1940) to be an adaptation P africanus, this hypertrophied and covers surface of the hand much (Fig 3C) aquatic to pad is greatly of the dorsal The presence of an elongate ovoid femoral gland, which is most evident in life because it often can be hardened and yellow in color, allows the BREVIORA &';'- ? "J' No 513 DIAGNOSING [RTHROLEPTIS AND PHRYNOBATRACHl :ik)n identification males of breeding (Blackburn, However, most in be difficult Breeding 2005; Phrynobatrachus froglets Stewart terrestrially deposited eggs In contrast, after Phrynobatrachus forms one or might preservation males have a when not single SLibgular vocal sac, which, distended, 1967) species, this gland identify to multiple folds, roughly parallel to the lower jaw, on the margins of the throat (Stewart, 1967; lateral Although Fig 3E) gular the Arthroleptis can be distended prominent gular are folds region of and wrinkled, not present (Fig 3D) from hatch small a of clutch most Phrynobatrachus species deposit hundreds to thousands of eggs ponds, in pools, and a small number of small clutches found in tree holes, in of eggs or streams, species deposit stagnant water in empty fruit capsules, within snail shells, or terrestrially (Rodel, and Rodel 1998; exhibiting these modes include Ernst, Species 2002) reproductive alternative P dendrobates, P guineensis P krefftii, P phyllophilus, P sandersoni, tokba, P For many S although have all and free-living biologists that regularly tadpoles (Amiet, 1981; Rodel, 1998; Rodel and Phrynobatrachus, it is obvious that the body proportions of these and Ernst, 2002) Although few advertisement calls of these genera are published, field collect Arthroleptis frogs generally differ Indeed, we find that those currently available will undoubtedly Arthroleptis have heads that are relatively assist in distinguishing wider than Phrynobatrachus Meristic data Arthroleptis collected in study this regression linear illustrate coefficients that differ the SVL) Thus, relative at least for larger specimens, the width of the head could be a useful quick diagnostic feature, especially if used in Phrynobatrachus from Drewes and Perret, 2000; Rodel, 2000; Schiotz, 1964) Although we demonstrate signifi- two genera However, in general, the difference in body proportions is only obvious in large specimens (> 30 mm cantly between these (e.g., that it is possible to this study distinguish adult in Phrynobatrachus and Arthroleptis with the use of morphological characters, the identification of juvenile and subadult Arthroleptis and Phrynobatrachus continues to be chal- lenging, even occasionally for the authors of concert with other morphological characters this study Fortunately, the identification discussed herein (Table numerous taxa has been 1) It is also important to note that numerous nonmorphological characters such as call breeding structure, biology, and habitat preference can also be used in the field to assist in the identification Phrynobatrachus lieved to illustrating 0.1 mm (MCZ in are in be- which recent Hebert et use a/., 2004; Vences et of DNA 2003; a!., barcoding Moritz and 2005) (e.g., Cicero, The use of the RNA (rRNA) mitochondrial 16S ribosomal gene has proven to be particularly successful in amplification et al, 2005) of amphibian We DNA found have (Vences that the left pedal digits III and IV of P tokba (MCZ A-26905) illustrating and circummarginal grooves F, Dorsal surface of A stenodactylus (MCZ A- 137060) the hourglass (i.e triple diadem) pattern G Dorsal surface of A sp nov (MCZ A-137978), in life, the median dorsal skin raphe H, Dorsal surface of P steindachneri (MCZ A- 136907) on left and P illustrating extensive auritus of Arthroleptis and Arthroleptis have direct development, expansion of illustrating All the of greatly facilitated by 2E digit webbing E, Tips of tip A-138095) on right illustrating variability in chevron-shaped glands Scale bar mm in 2A-D, F-H; BREVIORA So 513 Secondary sexual characters of males useful in distinguishing between Arthroleptis and Phrynoba3 A Right hand of A stenodactylus (MCZ A-137060) in ventral view showing elongate digit III B Fingers II and III of male A schubotzi (CAS 201717) in ventral view illustrating dermal spines C Right hand of male P natalensis (MCZ A-138084) above, and left hand of male P (Dimorphognathas) afrkanus (MCZ A-136757) below Figure trachus in dorsal view illustrating nuptial excrescence (pad) on digit I D Throat of male A schuborzHCAS 201717) of vocal folds E Throat of male P auritus 138095) and P (Phrynodon) sanderso?iH\\CZ A- 136790) illustrating visible vocal folds Scale bar mm A stenodaaylus (MCZ A-137061), right, illustrating lack left, (MCZ and A- AND PHRYNOBATRACHl DI.\ti\()M\ii IRTIIROLEPIIS 2IMIS amplification of this gene is identifying tadpoles, juveniles, effective V MORPHOLOGICAL CHARACTERS EXAMINED APPENDIX in and subadults of numerous African ranoid frogs, including Phrynobatrachus and Arthroleptis However, External Morphology molecular data and analyses can be con- founded b\ the misidentificatioD of voucher specimens For instance, nucleotide BLAST searches against GenBank sequence the Arthroleptis specimens for et al (2003) amplified the 16S rRNA (GenBank AF21 139^10) sequences Al- though Vences et al (2003) attribute the unusual paraphyly of Arthroleptis 16S genes to uncertainties in their result easily is sequence data, this thus are misidentified at the genus advocate DNA level We identification of specimens only to the level of genus because of the difficulty in accurately identifying species of Thorough taxonomic study in either genus combination with molecular data necessary before DNA will be identification can be used confidently to identify species of these two genera tarsus): (0) absent: Circummarginal groove or pedal digit some present ) ( tips: (0) species, this ( at present ) manual and/ absent: (1) present In groove present only on is the tips of the longest digits Variation in museum specimens might be the result of preservation, desiccation, or both explained: These sequences have high similarity to Phrynobatrachus and ( (0) absent: Heel tubercle (located at the proximal end of the gene reveals that these specimens are misidentified Tarsal tubercle: (0) absent: Outer metatarsal tubercle: present data for which Yences Pedal webbing: tary with absent or rudimen- (0) more than two distalmost phalan- ges of digit IV unwebbed: moderate to no more than the two distalmost phalanges of digit IV unwebbed ( ) extensive with Median dorsal ( ) skin raphe: (0) absent: present Hourglass or triple diadem pattern on dorsum: (0) absent: (1) present Chevron-shaped glands scapular in region: (0) absent: (1) present These ridges of skin can be short or can extend the entire ACKNOWLEDGMENTS length of the This study was supported by the Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology (Harvard Lniversity) and NSF grant EF0334939 (AmphibiaTree) to J Hanken Many thanks to the following individuals who made specimens under their care available for study: M Burger J Campbell D GunLaDuc L Cannatella B Clarke R Drewes R ther V Gvodzik T Harstell T Lawson S Loader P Malonza L MaziMcGuire J Measey A Ohler A Resetar J Rosado A Schmitz E Scott J Simmons L Trueb J Vindum, D Wake A buko Wynn on a Hanken provided useful draft of the manuscript present present Secondary Sexual Characteristics 10 Sexually mature males, relatively longer than third finger in females: (0) absent: (1) present 11 on Sexually mature males, dermal spines fingers: (0) absent: 12 13 ( ) present Sexually mature males, inguinal spines: (0) absent: J J body when Eyelid cornicle or spur: (0) absent: (1) ( ) present Sexually mature males, nuptial excres- cence (thickened pad of skin that can appear velvety) comments 14 (0) on first finger: (0) absent: ( ) present Sexually mature males, femoral glands: absent: (1) present Most often the BREVIOR-4 10 femoral glands of Phrynobatrachus are on the posterior thigh s Sexually mature males, lateral vocal lo- 15 However folds: glands can be situated closer to either the _ \o 513 or vent These glands are most easily ent, (0) absent: folds run lower seen in living specimens because they are the usually bright yellow crease> APPENDIX jaw throat, at and (1) present roughly the lateral form When parallel one pres- to margins or the of multiple DISTRIBUTION OF MORPHOLOGICAL CHARACTERS AMONG SPECIES OF ARTHROLEPTIS AND PHRY\OBATH4CHlS ALL CHARACTER STATES ARE BINARY (0, 1) MISSING DATA ARE CODED AS "?"; 0.1 DENOTES POLYMORPHISM REFER TO APPENDIX FOR CHARACTER DESCRIPTIONS 2008 DIAGNOSING ART/IROLEPTIS AND PHRYSOBATRACHIS APPENDIX Continued B RE 110 R 12 DNA barcodes Proceedings of the Royal Society of London Series B, 270: 313-321 Largen, M J 2001 The status of the genus Phrynobaand Eritrea including description of a new species (Amphibia i mi hits Gunther 1862 Ethiopia in Anura Ranidae) Tropical Zoology, — furt, — West Africa Volume I West African Savanna Frank- 2000 Herpetofauna of Amphibians of the Edition Chimaira, 332 pp and R Ernst , for A 2002 nonhatching nonfeeding, has — Revue de Zoologique Botanique assessment of amphibians 74-97, — Contribution l'osteologie a a et la systematique des rhacophorides africains Premiere Note Revue de Zoologique Botanique Africaine, Contribution 1941b a l'osteologie a et la systematique des ranides africains, Deuxieme Note Revue de Zoologique Botanique Africaine, 1954 35: Remarques sur le du Musee du Congo, Tervuren, genre Schoutedenella -4°, Zoologie, 1957 1: Revue de Hyperoliidae les Jr., E Standards 1985 I in Heal, and C E and herpetology Standard symbolic codes for institutional resource collections in herpetology and ichthyology Copeia, 1985: 802-832 Moritz, C, and C Cicero 2004 promise and pitfalls PLoS York, Dover Publications, Parker, H W 1935 A Annals Cameroons DNA Biology, 2: barcoding: 1529-1531 New xii + 577 new genus of and pp 1940 frogs from the Magazine Global patterns of F Bossuyt 2007 fication P S the in history of modern diversi- amphibians Academy of Sciences, of Natural Novitates of the frogs Zoologicae, family 42( ): 1-106 Perret, J.-L Les especes de Phrynobatrachus 1988 Sciences (Geneve), 41: 275-294 1998 A unknown in Guibe and Lamotte, African (Anura: The voices of some West African fra Dansk Naturhistorisk Forening 127: 35-83, Schmidt, K., and R Inger F 1959 Amphibians, and Hyperolius Exploration du Pare National de l'Upemba, Mission G F de Witte, Institut des Pares Nationaux du exclusive of the genera Afri.xalus Congo Beige, 56: 1-264, pis A Scott, E 2005 phylogeny of ranid frogs (Anura: based Ranidae), of morphological analysis on a simultaneous and molecular data Cladistics 21: 507-574 Stewart, M M 1967 Amphibians of Malawi New York Press, New ix + 163 pp — 1974 Parallel pattern polymorphism in the peia 1974: 823-832 Vences, M., J Kosuch, ranids: Ranidae) treefrogs: F Glaw, W Bohme, and M Molecular phylogeny of hyperoliid biogeographic origin of Malagasy and Seychellean taxa and re-analysis of familial paraphyly Journal of Zoology, Systematics, reproductive guineensis holes 1964 Veith 2003 (Anura, Ranidae) a eperon palpebral Archives des M.-O 104: 887-892 genus Phrynobatrachus (Amphibia: Ranidae) Co- The Australian Leptodactylidae 19-26 and Gower, M Wilkinson, J D Biju, K Guillaume, L Moriau, S York State University of History, 10: 401-404 tree Loader Ranoidea: Noble G K 1931 Biology of the Amphibia Rodel, Amnirana amphibians Videnskabelige Meddelelser R H Gibbs, E., ichthyology: part Simandou Range, southeastern Repubwith the description of a new species (Amphibia Anura Ranidae) Tropical Zoology, 17: 201-232, Schiotz A 34-40 Notes sur Dawson — conservation of Guinea, lic in Zoologique Botanique Africaine, 56: 274-282 Leviton A A Foret Classee du pis Witte Annales — 2004 in the Proceedings of the National 192-234, — and M A Bangoura Roelants, K., D 35: 85-110 pis — , Pic de Fon, pis 1941a 34: tadpoles Journal of Herpetology, 36: 121-125 systematique des ranides africains Premiere Note Africaine new reproductive mode genus Phrynobatrachus: Phrynobatrachus the alticola 287-306 14: F 1940 Contribution a l'osteologie et a la Laurent, R No 513 mode so far Phrynobatrachus 1961 breeds Herpetozoa in 11: and Evo- lutionary Research, 41: 205-215 — M Thomas, A van der Meijden, Y Chiari and D R Vieites 2005 Comparative performance , of the 16S rRNA gene amphibians Frontiers in in DNA Zoology barcoding of 2:  ... ridges of skin can be short or can extend the entire ACKNOWLEDGMENTS length of the This study was supported by the Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology. .. new genus of and pp 1940 frogs from the Magazine Global patterns of F Bossuyt 2007 fication P S the in history of modern diversi- amphibians Academy of Sciences, of Natural Novitates of the frogs... Proceedings of the Royal Society of London Series B, 270: 313-321 Largen, M J 2001 The status of the genus Phrynobaand Eritrea including description of a new species (Amphibia i mi hits Gunther 186 2