Research Article |
Corresponding author: Katherine E. Mullin ( mullink@cardiff.ac.uk ) Corresponding author: Pablo Orozco-terWengel ( orozco-terwengelpa@cardiff.ac.uk ) Academic editor: Angelica Crottini
© 2022 Katherine E. Mullin, Manoa G. Rakotomanga, Jeff Dawson, Frank Glaw, Andolalao Rakotoarison, Pablo Orozco-terWengel, Mark D. Scherz.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Mullin KE, Rakotomanga MG, Dawson J, Glaw F, Rakotoarison A, Orozco-terWengel P, Scherz MD (2022) An unexpected new red-bellied Stumpffia (Microhylidae) from forest fragments in central Madagascar highlights remaining cryptic diversity. ZooKeys 1104: 1-28. https://doi.org/10.3897/zookeys.1104.82396
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The Madagascan endemic subfamily Cophylinae in the family Microhylidae, is an example of a taxonomic group for which much is still to be discovered. Indeed, the cophyline frogs present a large portion of Madagascar’s cryptic and microendemic amphibian diversity, yet they remain understudied. A new red-bellied species of the microhylid frog genus Stumpffia is described from the central plateau of Madagascar. Visual encounter surveys in Ambohitantely and Anjozorobe in 2019 and 2020 identified this previously unknown Stumpffia species, which closely resembles Stumpffia kibomena known from Andasibe in the east. Stumpffia lynnae sp. nov. adds another species to the red-bellied species complex, differing from S. kibomena by genetic differentiation in the mitochondrial 16S rRNA gene (3.6–3.9%) and distinct nuclear RAG1 haplotypes, as well as strongly by its advertisement call. The new species is known from across Ambohitantely Special Reserve and Anjozorobe Angavo protected area, but is known only from one complete specimen and eight individual tissue samples. Based on the rarity of the species, the small number of locations in which it has been found, and its disappearing forest habitat, its IUCN Red List classification is suggested as “Endangered”. This species is the first Stumpffia described from Madagascar’s central plateau, highlighting the importance of conserving the remnant forest fragments in this area and the ongoing need to survey and protect this threatened habitat type.
Amphibian, cophyline, DNA barcoding, phylogeny, taxonomy
Madagascar is one of the world’s top biodiversity hotspots for conservation priority (
The three Madagascan endemic subfamilies of Microhylidae Günther, 1858; Dyscophinae Boulenger, 1882, Scaphiophryninae Laurent, 1946, and Cophylinae Cope, 1889; are examples of taxonomic groups for which much is still to be discovered. Indeed, the cophyline frogs present a large proportion of Madagascar’s cryptic and microendemic amphibian diversity (
Stumpffia contains most of the smallest cophyline frogs (
Prior to surveys in 2018 no Stumpffia species were known from Madagascar’s central plateau (Ambohitantely Special Reserve and surrounding forest fragments). Anilany helenae Vallan, 2000 from Ambohitantely Special Reserve was originally described as Stumpffia helenae (Vallan, 2000a), before a comprehensive revision of the Cophylinae determined this species to be in its own genus (
Visual encounter surveys in late 2018 (
Bright red colour on the venter is an interesting feature that has recently been highlighted as occurring in several different clades of frogs in Madagascar (
Geographically, the nearest occurring species of Stumpffia with a red belly is S. kibomena, described by
Here, we provide new data on the red-bellied Stumpffia species that has been found in both Ambohitantely and Anjozorobe. We find that it is morphologically and genetically most similar to Stumpffia kibomena, but that it differs substantially from that species genetically and especially in the male advertisement call. We therefore describe it as a new species, which represents the first species of the genus in the central highlands of Madagascar.
Visual encounter surveys (VES) were conducted during the day and evening throughout March – May 2019 and January – March 2020 in some of the last remaining forest blocks in Madagascar’s central highlands. Locations included six forest fragments in Ambohitantely Special Reserve (18.1960°S, 47.2865°E, elevation ~ 1600 m a.s.l.), the two forest fragments in Ankafobe protected area (18.1089°S, 47.1932°E, elevation 1475 m a.s.l.), forest at Anjozorobe (18.4095°S, 47.9447°E, elevation ~ 1350 m a.s.l.), and at Andasibe Mitsinjo (18.9335°S, 48.4129°E, elevation ~ 900 m a.s.l.) (Fig.
Map of Ambohitantely Special Reserve showing known Stumpffia lynnae sp. nov. distribution. A Ambohitantely, Anjozorobe, and Andasibe relative to one another B map of Madagascar showing the wider distribution of Stumpffia lynnae sp. nov. and its sister species Stumpffia kibomena, Stumpffia sp. Ca11 and Stumpffia sp. Ca34. Satellite imagery Google Earth (2015).
DNA was sampled from each individual using the less invasive buccal swab sampling technique, following the method of
DNA was extracted from the buccal swabs and storage lysis buffer using the Qiagen DNeasy kits following manufacturer’s protocol. We assembled phylogenies based on two mitochondrial gene fragments to assess the phylogenetic relationship between the newly collected material and other Stumpffia species, and built a haplotype network using one nuclear gene.
The 5’ fragment of 16S rRNA (~ 630 base pairs) was amplified using the 16SL3 and 16SAH primers as in
The recombination-activating gene 1 (RAG1) was used as a nuclear marker as it is known to show distinct haplotypes for closely related Stumpffia species (
Haplotypes were phased in DNAsp (
A fragment of mitochondrial Cytochrome Oxidase 1 (COI) was also amplified and sequenced, however given there is limited reference material from closely related species (1 sequence from Stumpffia sp. Ca34 and none from Stumpffia sp. Ca11 or S. kibomena), it was not analysed in detail here. The primers Chmf4 and Chmr4 were used to amplify a region of ~ 658 bp, using the same reaction volume and concentrations as above, and with PCR thermo-cycling conditions as in
Where possible the sequences of the same individual within each species were used throughout the 16S, RAG1 and COI analysis for consistency. All newly obtained sequences were deposited into GenBank (accession numbers are provided in Suppl. material
One advertisement call recording was made of a male observed with an inflated vocal sac in Anjozorobe. The call recording was made using the application RecForge II on a Samsung Galaxy A5 smartphone using its internal microphone, the file was saved as a .wav sound file. This male was swabbed, and DNA sequenced. Air temperature at the time of the call was recorded with a Kestrel 2500 weather meter. Call analysis was conducted in Audacity v. 2.3.3, following a call-centred approach, defining a call as the main coherent sound unit, separated from other such units by a distinct period of silence, with multiple calls strung together into a call series (
Throughout 880-person survey hours during both day and evening surveys, only eight individuals of the putative new Stumpffia species were observed, six from Ambohitantely and two from Anjozorobe (Table
Details of all Stumpffia lynnae sp. nov. samples from Ambohitantely (Amb) and Anjozorobe (Anj). ND: Not Determined.
Sample ID | Date | Location | Time | Coordinates | Elevation (m) | Forest type | Distance from water (m) | Substrate | Sex | SVL (mm) | Call | COI | 5’ 16S rRNA | RAG1 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
KAMUS60 | 13/04/19 | Amb | 10:15 | S18.1969, E47.2842 | 1586 | Slope | 10 | Leaf litter | Juvenile | 8.3 | – | X | X | X |
KAMUS74 | 16/04/19 | Amb | 19:29 | S18.1753, E47.3088 | 1408 | Riparian | 1 | Leaf litter | ND | 15.5 | – | X | X | – |
KAMUS167 | 12/05/19 | Amb | 11:10 | S18.2328, E47.2811 | 1522 | Slope | 5 | Soil under large rock | ND | 19.8 | – | X | X | X |
KAMUS200 | 16/05/19 | Amb | 08:50 | S18.1517, E47.2886 | 1532 | Slope | 5 | Leaf litter | ND | 11.3 | – | X | X | X |
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24/01/20 | Amb | 09:00 | S18.1517, E47.2886 | 1540 | Riparian | 5 | Leaf litter under pandans | ND | 20.9 | – | X | X | X |
KAMUS256 | 24/01/20 | Amb | 09:53 | S18.1517, E47.2886 | 1528 | Riparian | 5 | Leaf litter | ND | 16.0 | – | X | X | X |
KAMUS370 | 15/02/20 | Anj | 19:00 | S18.4116, E47.9501 | 1432 | Slope | ND | Leaf litter | F – gravid | 22.2 | – | X | X | X |
KAMUS371 | 15/02/20 | Anj | 19:00 | S18.4116, E47.9501 | 1432 | Slope | ND | Leaf litter | M – calling | 20.1 | X | X | X | X |
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12/19 | Amb | 08:30-11:00 | S18.1755, E47.2841 | 1560 | ND | ND | Bamboo node | ND | ~15-20 | – | – | – | – |
Maximum Likelihood analysis of the 5’ fragment of the mitochondrial 16S rRNA gene of the species included in the analysis yielded a phylogeny which reflected that seen in the comprehensive integrative taxonomy conducted by
Maximum Likelihood tree of Stumpffia spp. based on analysis of a 621 bp fragment of the mitochondrial 16S rRNA gene. MUSCLE alignment, General Time Reversible model plus Gamma distribution, all sites used, × 1000 bootstraps, SPR level 5, no variant sites. Purple labels mark the other red-bellied Stumpffia species. Photographs Mark D. Scherz and Frank Glaw.
Uncorrected pairwise distances (p-distances) estimated for the 16S sequences between specimens from Anjozorobe and Ambohitantely was 1.3%, while the within groups distances were 0.0% and 0.12%, respectively. The mean p-distance between the Ambohitantely individuals and the S. kibomena sequences was 3.9%, and between the Anjozorobe individuals and S. kibomena sequences was 3.6% (Suppl. material
Within the 16S alignment there are five differences that are unique to the putative new species (Suppl. material
The RAG-1 sequence (504 bp) was successfully obtained for seven out of the eight individuals from Ambohitantely and Anjozorobe. The sequences obtained show segregating genetic variation (five haplotypes) and one haplotype shared between Ambohitantely and Anjozorobe (Fig.
Haplotype network constructed from nuclear RAG-1 gene sequences (338 bp) of seven specimens of Stumpffia lynnae sp. nov. (two from Anjozorobe (Anj; yellow) and five from Ambohitantely (Amb; green)) and eight other closely related Stumpffia species from Clade C2 (
The COI phylogeny mirrors that of the 16S marker, and also forms a well-supported clade of the putative new species (100% bootstrap), with the Anjozorobe individuals divided into a well-supported subclade (99%). The putative new species is sister to Stumpffia sp. Ca34 (81% support). The phylogeny can be seen in Suppl. material
In summary, there is concordant evidence from two mitochondrial markers and a nuclear DNA fragment to support the species-level genetic distinction of the specimens from Anjozorobe and Ambohitantely, not just from Clade C2 species but also from all 27 described species of Stumpffia included in the analysis, as well as from the nearest currently known candidate species, Stumpffia sp. Ca11 and Stumpffia sp. Ca34.
The advertisement call of S. kibomena was described by
Acoustic traits of Stumpffia kibomena in comparison to those of S. lynnae sp. nov.
Species and source | Number of calls in series | Call – repetition rate (number calls/second) | Call duration (= note duration) (ms) | Duration of interval between calls (end-start) (ms) | Dominant frequency range (Hz) |
---|---|---|---|---|---|
S. kibomena ( |
11–22 (n = 5) | 1.2–1.3 | 70–76 (73±2, n = 9) | 770–813 (797±15, n = 9) | 3900–4300 |
S. kibomena (CD track measured by KM) | 21 | 1.2 | 68–82 (74.3, n = 8) | 742–766 (757, n = 7) | 3858–3883 |
Stumpffia lynnae sp. nov. (KM original recording) | 8 | 0.25 | 163–184 (174, n = 8) | 3498–5581 (4357, n = 7) | 2027–2044 |
Thus, in the following we provide a formal description of this new species, which is morphologically cryptic with respect to S. kibomena but genetically and bioacoustically distinct.
The new species is assigned to the genus Stumpffia based on its morphological and genetic affinities. Within the genus, it is distinguished by the unique combination of the following characters: (1) SVL 15.5–22.2 mm (adults in life), (2) limited digital reduction on the hands and feet such that first finger is reduced; other fingers not reduced and first toe is slightly reduced; other toes not reduced, (3) bright red to orange colouration confined to the ventral surfaces of the legs, posterior abdomen, and ventral arms, (4) absence of red markings on the lower jaw, and advertisement call with (5) inter-call intervals of 3498–5581 ms, (6) call/note duration 163–184 ms, (7) dominant frequency 2027–2044 Hz, and (8) distinct genetic divergence in the mitochondrial and nuclear genome to other known species.
Stumpffia lynnae sp. nov. can be distinguished from all other Stumpffia species except S. be, S. kibomena, S. meikeae, S. miovaova, S. nigrorubra, and S. roseifemoralis by the presence of bright red colouration on ventral surfaces of arms, legs, and abdomen. Among these species it can be distinguished from S. be by smaller body size (15.5–22.2 mm adults in life vs. 25.2 mm) and less expanded terminal discs on fingers and toes, as well as being in a different major clade of Stumpffia (Clade C rather than Clade A;
Stumpffia lynnae sp. nov. is morphologically almost indistinguishable from S. kibomena (Table
Morphological data of Stumpffia lynnae sp. nov. and Stumpffia kibomena (data for latter species from
Measurements (mm) |
S. lynnae sp. nov. Holotype |
/SVL |
S. kibomena holotype |
/SVL |
S. kibomena |
/SVL |
S. kibomena |
/SVL | |
---|---|---|---|---|---|---|---|---|---|
1 | SVL | 20.5 | 21.2 | 19.8 | 17.1 | ||||
2 | HW | 6.5 | 0.32 | 6.7 | 0.32 | 6.9 | 0.35 | 6.2 | 0.36 |
3 | HL | 5.0 | 0.24 | 5.1 | 0.24 | 4.9 | 0.25 | 4.3 | 0.25 |
4 | TD | 1.5 | 0.07 | 1.2 | 0.06 | 1.4 | 0.07 | 1.3 | 0.08 |
5 | ED | 2.0 | 0.10 | 1.9 | 0.09 | 1.6 | 0.08 | 1.6 | 0.09 |
6 | END | 1.5 | 0.07 | 1.9 | 0.09 | 1.7 | 0.09 | 1.3 | 0.08 |
7 | NSD | 0.5 | 0.02 | 1.1 | 0.05 | 0.8 | 0.04 | 0.8 | 0.05 |
8 | NND | 2.0 | 0.10 | 2.4 | 0.11 | 2.4 | 0.12 | 2.3 | 0.13 |
9 | FORL | 12.0 | 0.59 | 12.5 | 0.59 | 12.1 | 0.61 | 11.5 | 0.67 |
10 | HAL | 4.0 | 0.20 | 5.0 | 0.24 | 4.5 | 0.23 | 4.4 | 0.26 |
11 | HIL | 32.0 | 1.56 | 35.5 | 1.67 | 32 | 1.62 | 29.5 | 1.73 |
12 | FOTL | 14.5 | 0.71 | 15.3 | 0.72 | 14.7 | 0.74 | 14.8 | 0.87 |
13 | FOL | 8.5 | 0.41 | 10.0 | 0.47 | 8.9 | 0.45 | 9.2 | 0.54 |
14 | TIBL | 9.0 | 0.44 | 10.6 | 0.50 | 9.6 | 0.48 | 9.3 | 0.54 |
15 | RHL | Eye | Eye | Eye | Eye |
Direct comparison between the holotype of S. lynnae
Images of Stumpffia kibomena (top row from the species description of
A specimen in a good state of preservation, except for skin loss where left thigh tissue muscle was removed for tissue sample. The body is elongated with the head wider than long, but not wider than the body. The snout is roughly rounded in both dorsal and lateral views. The nostrils are not protuberant and are closer to the tip of the snout than the eye. The tympanum is distinct and large (75% of eye diameter), and the supratympanic fold is indistinct. First finger short, others not reduced (Fig.
Measurements (in mm). Snout-vent length 20.5, maximum head width 6.5, head length from tip of snout to posterior edge of snout opening 5.0, horizontal tympanum diameter 1.5, horizontal eye diameter 2.0, distance between anterior edge of eye and nostril 1.5, distance between nostril and tip of snout 0.5, internarial distance 2.0, forelimb length (from limb insertion to tip of longest finger) 12.0, hand length, to the tip of the longest finger 4.0, hind limb length (from the cloaca to the tip of the longest toe) 32.0, tibia length 9.0, foot length including tarsus 14.5, foot length 8.5 (Table
In life the dorsum was pale brown, with dark brown markings (Fig.
Seven additional frogs were sampled for DNA and basic measurements were taken. Details of these frogs and their collection sites are shown in Table
The calls were recorded from a male (KAMUS371) at Anjozorobe during heavy rainfall on the 15th of February 2020, at 19:30, at an air temperature of 20.5 °C. The male was calling while sitting on the leaf litter on a slope in primary forest close to a female. The male was not collected as a specimen due to lack of permits to allow this, but swabs for DNA analysis were collected. The advertisement call of S. lynnae sp. nov. is structurally similar to that of other Stumpffia species in that it is a single melodious note that is repeated at regular intervals in call series. The call is simple, with the call composed of a slightly amplitude-modulated single tonal note, with multiple calls repeated in series at regular intervals. The calls are evenly spaced across the call series with silent intervals between calls. A definitive number of calls per call series cannot be determined given the sample size of one recording. Frequency is distributed across one band for each note, and frequency modulation is relatively equal across the note. No harmonics were seen in this call recording. The individual emitted eight calls, with a call-repetition rate of 0.25 calls per second. Call/note duration was 163–184 ms, and the duration of intervals between calls was 3498–5581 ms (n = 7). The dominant frequency range was 2027–2044 Hz (Table
This species name is a matronym honouring Lynne Mullin, to whom we are pleased to dedicate this attractively colourful species in recognition of the unconditional support she has provided to the first author. The origin of Lynn/e is from Celtic language, with the meaning waterfall, pond, and lake. Given the popular waterfall in the centre of Ambohitantely Special Reserve where this species was first found, this name seems appropriate. The name has further relevance to this beautiful red-bellied frog with the Spanish meaning of the feminine name ‘pretty’. The species epithet is defined as a genitive noun with the ‘e’ removed for easier pronunciation.
While just eight individuals were recorded, the six at Ambohitantely were distributed across four fragments (three in addition to the core forest block) including a very small (3.5 ha) fragment at the southern end of the reserve (Fig.
The encounters of the nine frogs (including the one individual found by
This species is known to occur in two locations with different conservation situations. Ambohitantely Special Reserve, currently managed by Madagascar National Parks is highly fragmented, and is threatened by cattle grazing, illegal logging and forest activities, forest burning for charcoal, and forest fires and fire suppression activities (Goodman, Raherilalao and Wohlauser 2018 pp 1338–1340). The number of forest fragments surrounding the Reserve boundary has substantially declined since 1996 (
Under the IUCN Red List criterion B (Geographic range), we believe this species should be listed as Endangered for both B1, extent of occurrence (EOO), and B2, area of occupancy (AOO) (
Stumpffia lynnae is genetically and bioacoustically different to its close relative S. kibomena, to which it is morphologically very similar. This new species of Stumpffia brings the total number of known Stumpffia to 45, but given the similarity to S. kibomena, Stumpffia sp. Ca11, and Stumpffia sp. Ca34, also highlights the cryptic diversity that exists within the genus.
Madagascar presents high levels of amphibian micro-endemism (
The presence of S. lynnae in both Ambohitantely and Anjozorobe may provide evidence that these two forests were once connected. If these forests were once connected and the species existed across a larger range, this species may not have formerly exhibited micro-endemism. Its current AOO fits within the range of most Stumpffia, between 50 to 100 km2 (
A study of endemism in the Mantellidae family found that many sister species pairs did not have overlapping ranges, but there were some examples of young microendemic sister species occurring in full sympatry (
On the contrary, however, the latter finding of
This species adds another to the list of those with red markings, which occur in many different groups of frogs in Madagascar (
This new Stumpffia highlights the importance of continued survey effort in the central highlands, and adds another endemic species to the area, highlighting the need to protect the rapidly dwindling forest fragments. It also highlights the taxonomic research that is still required to fully understand the Stumpffia genus, with this species alone still requiring more knowledge. More individuals should be surveyed to understand more about their population size, distribution, and population trends as well as their life history and ecology.
We thank Cardiff University for ethical approval and the Madagascar Ministry of the Environment and Sustainable Development (MEDD) for providing our research permit No332/19/MEDD/SG/DGEF/DGRNE, and export permit No046N-EA03/MG20. We thank the Department of Animal Biology, University of Antananarivo for supporting the permits and larger project. We could not have conducted fieldwork without field guides Tovo Raditra from Madagascar National Parks and Shecene from Anjozorobe, and research assistants Minosoa L. C. Razafiarimanana (2020) and Malalatiana Rasoazanany (2019). We thank Durrell Wildlife Conservation Trust for providing financial and logistical support in the field. The UK Natural Environment Research Council supported this work through the GW4+ Doctoral Training Partnership NE/L002434/1. MDS was supported by a grant from the German Research Foundation (Deutsche Forschungs Gemeinschaft) SCHE 2181/1-1. The sequence data underlying this article are available in the GenBank Nucleotide Database at https://www.ncbi.nlm.nih.gov/genbank/, and can be accessed with accession numbers 5’ 16S rRNA ON314863–ON314871, 3’16S ON332822–ON332828, COI ON313699–ON313706, RAG1 ON323575–ON323581 (details in Suppl. material
Figure S1
Data type: docx file
Explanation note: Maximum Likelihood phylogeny of selected Stumpffia species using a 624 bp region of the COI mitochondrial marker, using the HKY+G+I model with 1000 bootstrap replicates.
Figure S2
Data type: docx file
Explanation note: Sections of the 16S rRNA gene alignment, showing the differences of Stumpffia lynnae sp. nov. in comparison to 27 other Stumpffia species from across the Stumpffia phylogeny.
Table S1
Data type: docx file
Explanation note: GenBank accession numbers.
Table S2
Data type: docx file
Explanation note: Pairwise uncorrected distances between the 27 Stumpffia species used in the 16S phylogeny.