[Herpetology • 2012] Morphology, function and evolution of the pseudothumb in the Otton frog Babina subaspera | endemic frog to the Amami Islands of south Japan

Abstract

Frogs and toads normally have four toes on the forelimbs and five on the hindlimbs. An exception is the Otton frog Babina subaspera, which has regained the pseudothumbs. The morphology and use of pseudothumbs in Otton frogs were compared between the sexes. The pseudothumbs, which are longer and thicker in males than in females, encase a prepollical spine that occasionally cuts through the tissue as it is projected from the sheath. The males had visible spines and demonstrated a jabbing response more often than did females. Males were observed to use their pseudothumbs in male–male combat over females or breeding nests, as well as during amplexus. There was no evidence that females use their pseudothumbs. It is suggested that pseudothumbs first evolved as an anchor for amplexus, but that they are now used as a weapon in combat as well, giving males higher fitness. The study of pseudothumbs in the Otton frog will facilitate further study of related topics of interest, including extra fingers in vertebrates, self-damaging structures and developmental constraints in the hands.

Keywords: Babina subaspera; hand morphology; male–male combat; prepollical spine; sexual dimorphism

Japanese's Otton frog Babina subaspera

Japanese Otton frog Babina subaspera, claw close-up 

The Otton frog’s hidden claw is exposed. (Image: N. Iwai)

Figure 6. A couple of Otton frog Babina subaspera captured just after egg-laying. A spine projecting from a pseudothumb was jabbed into the side of the female.

The innocent looking “Wolverine” frog conceals its hidden claws (Image: N. Iwai)

The Deadly Thumbs of Japanese Flick Knife Frogs http://on.natgeo.com/Vo7ZaC

Iwai, N. 2012. Morphology, function and evolution of the pseudothumb in the Otton frog. Journal of Zoology. DOI: 10.1111/j.1469-7998.2012.00971.x/ 

[Herpetology • 1991] Brookesia valerieae • Field observations on some dwarf chameleons (Brookesia spp.) from rainforest areas of Madagascar, with the description of a new species

Six species of Brookesia dwarf chameleons were recorded during two rainforest expeditions in Madagascar. One of these is described as a new species Brookesia valerieae based on the arrangement of the nine pairs of dorso-lateral spines, the lack of a pelvic shield, and dorsal chevron markings. Observations were made on the defence and roosting behaviours shown by these six species. Aspects concerning the evolution and conservation in Madagascar are discussed for this poorly studied group of endemic Malagasy reptiles.



Brookesia valerieae sp. nov.
Holotype- Adult female, BM(NH) 1988.8, Manongarivo Special Reserve, north-west Madagascar, 14" 4' S, 48" 17' E, 350 m altitude, caught on the forest floor at midday by N. Quansah, collected by C. J. Raxworthy, 17.2.88.
The holotype is shown in Plates V and VI. It has been deposited at the British Museum (Natural History).


Etymology: This species of chameleon has been named for Valerie M. Raxworthy in recognition of her support towards this work in Madagascar.

Raxworthy, C. J. 1991. Field observations on some dwarf chameleons (Brookesia spp.) from rainforest areas of Madagascar, with the description of a new species. J. Zool., London 224: 11-25.

http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.1991.tb04785.x/abstract

[Herpetology • 2012] new species in Brookesia minima group • Discovery of Miniaturized and Microendemic New Species of Leaf Chameleons (Brookesia) from Northern Madagascar

Adult specimens of newly described species in life.

(A) male and (B) female of Brookesia tristis from Montagne des Français; 

(C) male and (D) female of Brookesia confidens from Ankarana; 

(E) male and (F) female of Brookesia micra from Nosy Hara; 

(G) male and (H) female Brookesia desperata from Forêt d'Ambre.

Abstract 

Background

One clade of Malagasy leaf chameleons, the Brookesia minima group, is known to contain species that rank among the smallest amniotes in the world. We report on a previously unrecognized radiation of these miniaturized lizards comprising four new species described herein.

Methodology/Principal Findings

The newly discovered species appear to be restricted to single, mostly karstic, localities in extreme northern Madagascar: Brookesia confidens sp. n. from Ankarana, B. desperata sp. n. from Forêt d'Ambre, B. micra sp. n. from the islet Nosy Hara, and B. tristis sp. n. from Montagne des Français. Molecular phylogenetic analyses based on one mitochondrial and two nuclear genes of all nominal species in the B. minima group congruently support that the four new species, together with B. tuberculata from Montagne d'Ambre in northern Madagascar, form a strongly supported clade. This suggests that these species have diversified in geographical proximity in this small area. All species of the B. minima group, including the four newly described ones, are characterized by very deep genetic divergences of 18–32% in the ND2 gene and >6% in the 16S rRNA gene. Despite superficial similarities among all species of this group, their status as separate evolutionary lineages is also supported by moderate to strong differences in external morphology, and by clear differences in hemipenis structure.

Conclusion/Significance

The newly discovered dwarf chameleon species represent striking cases of miniaturization and microendemism and suggest the possibility of a range size-body size relationship in Malagasy reptiles. The newly described Brookesia micra reaches a maximum snout-vent length in males of 16 mm, and its total length in both sexes is less than 30 mm, ranking it among the smallest amniote vertebrates in the world. With a distribution limited to a very small islet, this species may represent an extreme case of island dwarfism.

Figure 1. Map of northern Madagascar showing distribution of species of the Brookesia minima group.

Type localities in bold, B. dentata, B. exarmata, B. karchei, B. peyrierasi, and B. ramanantsoai not included, because their ranges are located further south; see inset maps in Fig. 2. Orange (dry forest) and green (rainforest) show remaining primary vegetation in 2003–2006, modified from the Madagascar Vegetation Mapping Project (http://www.vegmad.org).

Figure 2. Phylogenetic relationships among species of the Brookesia minima group based on mitochondrial DNA sequences.

Figure 9. Life history and morphology of Brookesia desperata.

(A) Female (displaying stress colouration) with two recently laid eggs. (B) Figure showing well-developed pelvic spine (1) and lateral spines on tail (2).

Figure 8. Brookesia micra sp. n. from Nosy Hara, northern Madagascar.

(A) adult male on black background, showing orange tail colouration; (B) juvenile on finger tip; (C) juvenile on head of a match; (D) habitat along a small creek on western flank of Nosy Hara, where part of the type series was collected.

Figure 6. Hemipenes of species in the Brookesia minima group.

Glaw, F.; Köhler, J. R.; Townsend, T. M.; Vences, M. 2012. Salamin, Nicolas. ed. "Rivaling the World's Smallest Reptiles: Discovery of Miniaturized and Microendemic New Species of Leaf Chameleons (Brookesia) from Northern Madagascar". PLoS ONE 7 (2): e31314. doi:10.1371/journal.pone.0031314

Glaw, F., M. Vences, T. Ziegler, W. Bohme, and J. Kohler. 1999. 1999. Specific distinctness and biogeography of the dwarf chameleons Brookesia minima, B. peyrierasi and B. tuberculata (Reptilia: Chamaeleonidae): evidence from hemipenal and external morphology. Journal of Zoology 247: 225-238.  http://www.zsm.mwn.de/her/pdf/64_Glaw_et_al_1999_Brookesia_minima_group.pdf

[Herpetology • 1995] 6 new Brookesia | B. ambreensis, B. antakarana, B. lineata, B. lolontany, et. al. • Systematics, speciation and biogeography of the dwarf chameleons (Brookesia; Reptilia, Squamata, Chamaeleontidae) of northern Madagascar

Brookesia ambreensis 

photo from: http://reptile-database.reptarium.cz/

Brookesia dwarf chameleons, endemic to Madagascar, were surveyed at  the following localities in  northern  Madagascar (north of 16”s): Montagne  d’Ambre, Ankarana, Manongarivo, Tsaratanana, Marojejy and Masoala. A total of 15 species occur in this region. Six new species are  described  and five new synonyms are identified. The genus Brookesia, the most speciose chamaeleontid genus in Madagascar, contains 23 species. 

Almost all the northern Brookesia species are restricted to rainforest and occupy a relatively narrow elevational range. Although the northern rainforests represent just one-third of the total rainforest and  about 5 %  of the total island  area,  65%  of the Brookesia species occur in this region, and 52% are endemic t o  the northern rainforest. Five new biogeographic regions of the northern rainforest are identified based on centres of Brookesia endemicity: Montagne d’Ambre, Northwest, Tsaratanana, Northeast and East. Speciation is thought to have been facilitated in the  north  through geographic isolation, with  the  Tsaratanana mountain range and the dry forests south of Montagne d’Ambre forming barriers  to dispersal,  and the Tsaratanana mountains acting as a centre of isolation. The fragmented distribution of several Brookesia species of low altitude rainforest suggests a period in Madagascar’s history when the climate was wetter and low altitude rainforest much more widespread. 

Brookesia ambreensis sp. nov. 

Holotype- UMMZ  203635,  mature  male,  collected  8  January  1992,  Antomboka  River, Montagne D’Ambre National  Park,  12’29’5  49” lO’E,  670 m  altitude,  Antsiranana Fivondronana, Antsiranana (Diego Suarez) Province, Madagascar,  by J.B. Ramanamanjato,  A. Raselimanana and C.J. Raxworthy.

Etymology- The  specific name refers to the type locality Montagne d’Ambre. 

Habitat and  distribution.- All  specimens collected  in  primary rainforest. All known specimens were collected between 650 and 1150m altitude a t  Montagne  d’Ambre, within the National Park and Parcel 2 of the Special Reserve. This species is probably endemic to  Montagne d’Ambre.

Brookesia antakarana sp. nov. 

Holotype- UMMZ  200071,  mature male, collected  6  December  1991, Antomboka  River, Montagne d’Ambre National Park,  12’32’S, 49’10’E,  1050 m altitude, Antsiranana Fivondronana, Antsiranana  (Diego Suarez) Province, Madagascar, by J.B. Ramanamanjato, A. Raselimanana and C.J. Raxworthy.

Etymology- The specific name refers to the Antakarana people and region of northern Madagascar, where this species appears to be restricted. 

Habitat  and  distribution- All  known specimens were collected in rainforest between  50-1200 m altitude  at Montagne d'Ambre, within the National Park and from Parcel 2 of the Special Reserve. This species is probably endemic to Montagne d'Ambre. 

Brookesia bekolosy sp. nov. 

Holotype- UMMZ  200078, mature male, collected 8 March  1992, Bekolosy, Manongarivo Special Reserve, 14"03'S, 48" 1 S'E,  1200 m altitude, Ambanja Fivondronana, Antsiranana (Dikgo Suarez) Province, Madagascar, by C.J. Raxworthy.

Etymology- The specific name refers to the type locality, the Bekolosy Plateau at  Manongarivo. 

Habitat and distribution- The  holotype was collected at 22:00 h, roosting on a thin branch at 1 m height, in primary rainforest at 1200m altitude on a ridge. No other locality is presently known  for  this species. The rainforest  a t  Berkolosy is  high altitude, with the forest  canopy typically between  5-10m in height,  and  tree branches  heavily  draped  with lichens. A more intensive survey was made by us at lower elevation forests in the Manongarivo Reserve (between 50-800m).  The absence of this species a t  these lower altitudes makes us think it is restricted to higher  elevation forest,  probably  in  excess  of  1000m. This species is  probably  restricted  to rainforest in the Northwest biogeographic region (see below). 

Brookesia brygooi sp. nov .  

Holotype- MHNP 8219,  female, collected  at  Analavelona, Southwest  Madagascar by H.  Humbert.

Etymology- The  specific name honours Dr  E.  R. Brygoo, who first described specimens of this new species, and contributed to the understanding of Brookesia systematics. 

Habitat and distribution- In  addition  to the localities given for the holotype, paratype  and other specimens, Brygoo (1 978) reported specimens (without calalogue numbers) from Bemaraha (Rtserve Naturelle IntCgrale No. 11) and Antsalova, also in the Southwest, Brookesia brygooi is found  in  the arid  Southwest  and  West  of  Madagascar,  occurring between  17-23"S,  and  is probably restricted t o  native deciduous forests in these regions. Brookesia brygooi is one of the few  arid-adapted species of the genus. The other species found in arid habitats of the Western Domain are B. bonsi, B. decaryi, B. perarmata  and B. stumpfi. 

Brookesia lineata sp. nov. 

Holotype- UMMZ  200073, mature male, collected 8 March  1992, Bekolosy, Manongarivo Special Reserve, 14"03'S, 48" 18'E, 1200 m altitude, Ambanja Fivondronana, Antsiranana (Diego Suarez) Province, Madagascar, by A. Raselimanana. 

Etymology- The  specific name refers t o  the unusual dark lines on the body of this species. 

Habitat and distribution- The  holotype was collected a t  night, roosting on a leaf a t  1 m height, in primary rainforest  a t  1200 m altitude on a ridge. No other locality is presently known for this species. For additional information see comments on habitat for Brookesia bekolosy. 

Remarks- Brookesia lineata is unusual in that  the flanks are marked  by  bold, dark brown, longitudinal lines. Brygoo (1978) does  not  describe such  a coloration pattern for any other Brookesia species, although dark flank lines occur in male Brookesia thieli (UMMZ 196217-8). 

Brookesia lolontany sp. nov. 

Holotype- UMMZ  203629,  mature  female, collected  29  March  1993, Matsabory  Lake, Tsaratanana,  14"09/S, 48"58/E, 2050 m altitude,  Bealanana  Fivondronana,  Mahajanga Province, Madagascar, by Angeluc Razafimanantsoa. 

Etymology- The  specific name “lolontany” is  the Malagasy name of  the Tsaratanana mountain spirits that are believed to occupy the forests where the types were collected. 

Habitat  and distribution- UMMZ  203629 collected at  20:00h, roosting on a leaf at 0.7m height, in bamboo dominated primary rainforest; UMMZ  203630 collected at  20:00 h, roosting on  a branch  a t   0.05m  height, in  primary rainforest.  Both specimens were  collected  in  the Tsaratanana mountain range, which includes the highest mountain in Madagascar, Maromokotro,  at  2876m altitude. The holotype of Brookesia lolontany was collected at  a higher altitude than any other Brookesia species. This species is probably restricted to  high altitude rainforest in the Tsaratanana Mountains. 

Remarks- The only other species known to occur at a similarly high elevation is Brookesia nasus, which  has been collected up to 1650m altitude at Andringitra. The latter species is morphologically the most similar species to Brookesia lolontany. 

Raxworthy, C. J. & R. A. Nussbaum 1995. Systematics, speciation and biogeography of the dwarf chameleons (Brookesia; Reptilia, Squamata, Chamaeleontidae) of northern Madagascar. J. Zool., London 235: 525-558. http://deepblue.lib.umich.edu/bitstream/2027.42/75501/1/j.1469-7998.1995.tb01767.x.pdf