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| Limnonectes bagoensis Köhler, Zwitzers, Than et Thammachoti, in Köhler, Zwitzers, Than, Gupta, Janke, Pauls et Thammachoti, 2021. DOI: 10.3390/d13090399 |
Abstract
Striking geographic variation in male advertisement calls was observed in frogs formerly referred to as Limnonectes doriae and L. limborgi, respectively. Subsequent analyses of mtDNA and external morphological data brought supporting evidence for the recognition of these populations as distinct species. We describe two new frog species of the genus Limnonectes (i.e., L. bagoensis sp. nov. and L. bagoyoma sp. nov.) from Myanmar. Limnonectes bagoensis sp. nov. is closely related to L. doriae whereas L. bagoyoma sp. nov. is closely related to L. limborgi. Results of this integrative study provide evidence for the presence of additional undescribed species in these species complexes but due to the lack of bioacoustical data, we consider these additional diverging populations as candidate species that need further study to resolve their respective taxonomic status. Both new species are distributed in Lower Myanmar. Limnonectes doriae is restricted to southern Myanmar along the Malayan Peninsula whereas L. limborgi is known to occur in eastern Myanmar and northwestern Thailand. The remaining populations formerly referred to as either L. doriae or L. limborgi are considered representatives of various candidate species that await further study. We further provide a de novo draft genome of the respective holotypes of L. bagoensis sp. nov. and L. bagoyoma sp. nov. based on short-read sequencing technology to 25-fold coverage.
Keywords: bioacoustics; cryptic species diversity; Dicroglossidae; genome; Limnonectes bagoensis sp. nov.; Limnonectes bagoyoma sp. nov.; Myanmar; new species; Thailand
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| Figure 11. Holotype of Limnonectes bagoensis n. sp. (SMF 104090) in life, at its calling site after the covering rocks had been removed. |
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| Figure 10. Limnonectes bagoensis n. sp. in life. (A) Male holotype, SMF 104090; (B) female paratype, SMF 104091; (C–F) male paratype, SMF 106038. Photos by Gunther Köhler. |
Limnonectes bagoensis sp. nov.
Gunther Köhler, Britta Zwitzers, Ni Lar Than and Panupong Thammachoti
Diagnosis. A species of the genus Limnonectes to which it is assigned because of its inferred phylogenetic position, males with hypertrophied heads, and the presence of odontoids on the lower jaw in adult males. Limnonectes bagoensis sp. nov. is assigned to the subgenus Elachyglossa because of its close phylogenetic position to the type species of this subgenus (i.e., L. gyldenstolpei). Limnonectes bagoensis sp. nov. differs from all congeners by having (1) a medium body size (males 32–49 mm; females 30–47 mm); (2) slightly enlarged toe disks; (3) adult males with small odontoids in the lower jaw; (4) adult males without a knob-like or flap-like structure (caruncle) in the interorbital and parietal region; also lacking swelling in the occipital region; (5) in adult males head not conspicuously enlarged; (6) webbing formula I 1–2 II 1–2.4 III 1.2–3 IV 3.3–2 V to I 1.8–2.2 II 1.5–2.8 III 2.2–3.2 IV 3.5–2 V; (7) a feeble dermal fringe along the outer edge of Toe 5; (8) male advertisement call consists of two portions that are separated by a break of slightly less than 1 s. The first portion of the call is a single note with a duration of 225–291 ms whereas the second portion consists of 4–9 notes with a duration of 1200 (4 notes) to about 2000 ms (9 notes) with about 4.5 notes per second; the dominant frequency is at 861–990 Hz (mean 945 Hz). Limnonectes bagoensis differs from all other species currently assigned to the subgenus Elachyglossa except L. doriae by lacking a knob-like or flap-like structure (caruncle) in the interorbital and parietal region in adult males (versus such structure present in adult males), and also lacking swelling in the occipital region (versus such swelling present in adult males). Limnonectes bagoensis differs from L. doriae in having a male advertisement call that consists of two portions, separated by a break of slightly less than 1s, the second portion with a series of 4–9 notes at about 4.5 notes per second (versus a single series of notes in L. doriae with about 12 notes per second); gular coloration in adult males not dark (versus gular region dark gray in adult males of L. doriae).
Etymology. The species name “bagoensis” refers to the city of Bago where the holotype of this species was collected, and -ensis denoting place.
Natural history notes. At the type locality at night time, adult males were heard calling on the surface hidden under flat rocks. Figure 11 shows the holotype (SMF 104090) that continued calling even after the covering rocks had been removed. Additional individuals were encountered sitting on the forest floor at night without cover.
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| Figure 14. Limnonectes bagoyoma n. sp. in life. (A) Female holotype, SMF 106034; (B) Male paratype, SMF 106035. Photos by Gunther Köhler. |
Limnonectes bagoyoma sp. nov.
Gunther Köhler, Britta Zwitzers, Ni Lar Than and Panupong Thammachoti
Diagnosis. A species of the genus Limnonectes to which it is assigned because of its inferred phylogenetic position (Figure 1), males with hypertrophied heads, and the presence of odontoids on the lower jaw in adult males. Limnonectes bagoyoma sp. nov. is assigned to the subgenus Taylorana because of its close phylogenetic position to the type species of this subgenus (i.e., L. limborgi; Figure 1). Limnonectes bagoyoma sp. nov. differs from all congeners by having (1) a small body size (males 29.3–30.7 mm; females 23.1–26.6 mm); (2) males with slightly enlarged odontoids; (3) inner metatarsal tubercle large, raised, usually >0.5 length of the first toe; (4) webbing formula I 1–2 II 1–2.4 III 1.2–3 IV 3.3–2 V to I 1.8–2.2 II 1.5–2.8 III 2.2–3.2 IV 3.5–2 V; (5) females with clutches of enlarged, non-pigmented eggs; (6) male advertisement call consisting of a single note with a duration of 220–250 ms and a dominant frequency mostly in the 1300–1400 Hz range. Limnonectes bagoyoma differs from the remaining species of the subgenus Taylorana as follows: from L. limborgi by having a male advertisement call consisting of a single note with a duration of 220–250 ms (versus call consisting of a series of 3–5 notes, each note with a duration of usually >260 ms in L. limborgi), and no dark lateral face mask (versus dark face mask present). Limnonectes bagoyoma differs from L. hascheanus by its larger body size, reaching 30 mm SVL in adult males (versus SVL <26 mm in both sexes in L. hascheanus), and by having more toe webbing, usually three phalanges free of webbing on the medial side of Toe 4 (versus more than three phalanges free of webbing on the medial side of Toe 4). Limnonectes bagoyoma differs from L. liui by its smaller body size, SVL not exceeding 31 mm in both sexes (versus SVL 32.0–38.5 mm in males of L. liui, only female in type series measuring 32.7 mm), toe webbing well-developed (versus rudimentary), and inner metatarsal tubercle usually >0.5 length of the first toe (versus “just half” of the first toe in L. liui). Limnonectes bagoyoma differs from L. medogensis by having the nostril positioned closer to the snout than to the eye (versus closer to eye in L. medogensis), vomerine teeth present (versus absent), venter patternless (versus marbled markings present), toe webbing well-developed (versus rudimentary), inner metatarsal tubercle distinctly shorter than the first finger (versus about length of Toe 1), and tarsal fold indistinct but present (versus absent). Limnonectes bagoyoma differs from L. xizangensis by having the toe tips enlarged into small disks (versus toe tips pointed), vomerine teeth present (versus absent), toe webbing well-developed (versus absent), and the presence of tiny tubercles on the dorsal surface of the shank (versus smooth), venter patternless (versus black reticulated markings present), and smooth skin on venter (granular skin on venter). Limnonectes bagoyoma differs from L. alpinus by having the toe webbing well-developed (versus toe webbing absent in L. alpinus), vomerine teeth present (versus absent), and tympanum distinct (versus hidden).
Etymology. The species name “bagoyoma” refers to the type locality Bago Yoma, a large but relatively low mountain range that runs in a north-south direction between the Irrawaddy (=Ayeyarwady) and the Sittaung River in Myanmar. It is likely that Limnonectes bagoyoma is geographically restricted to this mountain range.
Natural history notes. At the type locality, the specimens were collected during the daytime in leaf litter in the rainforest. The two males we collected were heard calling before we caught them. Each male was sitting in a shallow depression, covered by leaf litter. Other frog species collected at the type locality include Duttaphrynus melanostictus, Fejervarya orissaensis, Ingerana tenasserimensis, Limnonectes bagoensis, and Leptobrachium smithi.
Gunther Köhler, Britta Zwitzers, Ni Lar Than, Deepak Kumar Gupta, Axel Janke, Steffen U. Pauls and Panupong Thammachoti. 2021. Bioacoustics Reveal Hidden Diversity in Frogs: Two New Species of the Genus Limnonectes from Myanmar (Amphibia, Anura, Dicroglossidae). Diversity. 13(9); 399. DOI: 10.3390/d13090399
