Mantidactylus tricinctus ( Guibé, 1947 )

Scherz, Mark D., Crottini, Angelica, Hutter, Carl R., Hildenbrand, Andrea, Andreone, Franco, Fulgence, Thio Rosin, Köhler, Gunther, Ndriantsoa, Serge Herilala, Ohler, Annemarie, Preick, Michaela, Rakotoarison, Andolalao, Rancilhac, Loïs, Raselimanana, Achille P., Riemann, Jana C., Rödel, Mark-Oliver, Rosa, Gonçalo M., Streicher, Jeffrey W., Vieites, David R., Köhler, Jörn, Hofreiter, Michael, Glaw, Frank & Vences, Miguel, 2022, An inordinate fondness for inconspicuous brown frogs: integration of phylogenomics, archival DNA analysis, morphology, and bioacoustics yields 24 new taxa in the subgenus Brygoomantis (genus Mantidactylus) from Madagascar, Megataxa 7 (2), pp. 113-311 : 253-255

Mantidactylus tricinctus ( Guibé, 1947)

Type material.— Gephyromantis tricinctus Guibé, 1947 was originally described based on two syntypes: MNHNP 1931.26‒27 . As discussed by Glaw and Vences (1999), Guibé (1947) considered the female MNHN 1931.26 as ‘gynétype’ and the male MNHN 1931.27 as ‘androtype’ (see Frizzell 1933) whereas the other four specimens of the original series of G. tricinctus , containing the following specimens: MNHN 1931.26A (relabelled MNHN 1994.611 ), and MNHN 1931.26B (relabelled MNHN 1994.612 ) from Befotaka ; and MNHN 1931.27A (relabelled MNHN 1994.613 ), and MNHN 1931.27B (relabelled MNHN 1994.614 )from Vondrozo , all collected by R. Decary, were expressly indicated as ‘paratypes’ and thus are not name-bearing specimens. Guibé (1950) considered the ‘gynétype’ and the ‘androtype’ each as holotype, but as the nomen then was based on two specimens, these have to be considered syntypes. The nomen is currently based on lectotype MNHN 1931.26 designated by Blommers-Schl̂sser and Blanc (1991) .

Identity.— Glaw and Vences (1999) resurrected M. tricinctus which was previously considered a synonym of M. biporus (see Blommers-Schl̂sser & Blanc 1991) based on new material from An’Ala. The genetic data presented herein suggest three morphologically similar deeply divergent mitochondrial lineages that conform with the lectotype (and paralectotypes) of tricinctus in their morphological characters (e.g. small body size, reduced webbing). Our attempts of barcode fishing from the lectotype was unsuccessful and the few 16S reads obtained were inconclusive, probably contaminated with Homo sapiens reads. However, we succeeded in PCRamplifying and sequencing 16S from a specimen (ZSM 176/2006 = MVTIS 16559) from the Midongy du Sud National Park ( Bora et al. 2007) (also known as BefotakaMidongy), and thus presumably from very close to the type locality. Based on the phylogenetic position of this sample, we circumscribe M. tricinctus to a lineage known from Midongy, Manombo Special Reserve, and Ambahavala in the Anosy Mountains, and consider the lineages from the southernmost Southern Central East, and from the Northern Central East, as two new species named below.

Additional material. —ZSM 176/2006 (BOR 1066), adult male, and ZSM 177/2006, adult female, collected by P. Bora between September and October 2005 in BefotakaMidongy National Park (precise coordinates unavailable); ZSM 2377/2007 (ZCMV 5444), adult female, and ZSM 2415/2007 (ZCMV 5420), adult male, collected by M. Vences, G. Safarek, E. Rajeriarison, and T. Rajeriarison on 23 February 2007 1 km south of ‘site 2’, Manombo Special Reserve (precise coordinates not taken).

Diagnosis.—A member of the M. tricinctus clade as revealed by the phylogenomic analysis, and sister to M. grubenmanni sp. nov. described below. See Table 4 for a list of diagnostic morphological characters. The combination of very small body size (below 20 mm male SVL), connected lateral metatarsalia, reduced webbing, presence of a light (often yellowish) marking on snout tip, a yellow inguinal marking, and a short, pulsed advertisement call emitted in rapid succession in regular series, readily distinguishes M. tricinctus from all other nominal species of Brygoomantis . Most similar to its sister species M. grubenmanni sp. nov. and to a lesser degree, to M. gudrunae sp. nov.; for comparisons, see the diagnoses of these species below. For detailed distinction from other new species described herein, see the respective species accounts. A full list of molecular diagnostic sites in the 16S gene of M. tricinctus in pairwise comparisons to all other Brygoomantis species is provided as Supplementary appendix.

Variation.—Variation in measurements is given in Table 9. See Fig. 57 for colouration in life. There is weak sexual size dimorphism (confirmed male SVL 16.8–19.2 mm [n = 6] vs confirmed female SVL 18.0– 23.4 mm [n = 3]). Males have a larger tympanum than females (HTD/ED ratio is 59–73% in females, 73–105% in males). Femoral glands in males not very prominent, with a yellowish tone in life.

Natural history.—At Manombo, males were heard emitting their advertisement calls from the shore of slowmoving streams in degraded rainforest.

Calls.—The advertisement call of M. tricinctus , recorded on 23 February 2007 at Manombo, at an estimated air temperature of 25°C, consisted of a short, pulsed note, emitted in regular series at very fast succession ( Fig. 58 ). Amplitude modulation was present, with relative amplitude increasing from the beginning of the call, reaching its maximum with the terminal pulse. Numerical parameters of 64 analysed calls were as follows: call duration (= note duration) 45–113 ms (83.4 ± 19.0 ms); 8–19 pulses per note (15.5 ± 3.6); pulse duration 2–5 ms (2.8 ± 1.1); pulse repetition rate within notes 147.1–214.3 pulses/s (177.2 ± 27.7); dominant frequency 2787–2906 Hz (2851 ± 59 Hz), with a second peak of almost equal energy at ca 2100–2200 Hz; prevalent bandwidth 1400–5300 Hz; call repetition rate (= note repetition rate) within regular series ca 470– 580 calls/min. Call series consist of 35–42 calls (n = 3), but calls were also emitted isolated (possibly territorial function) or in short groups containing 2–3 calls.

Tadpoles.— The tadpole of this species has not been described.

Distribution.— Endemic to the South East ( Fig. 7 ).

This species is known from Ambahavala, Midongy du Sud/Befotaka-Midongy National Park (type locality), and Manombo. Elevation range: 30–900 m a.s.l.

Etymology.—Latin adjective formed from the stems ‘tri’ meaning ‘three’ and ‘cinctus’ meaning ‘crowned’ or ‘girded’, presumably in reference to the colour pattern.

Figures

FIGURE 7. Mantidactylus subgenus Brygoomantis species distribution based on verified records, divided by clade (Mantidactylus stelliger sp. nov. is presented alongside the inaudax clade for practicality). Colours for species correspond to those in Figs 2 and 4. Inset map shows the geographic regions of Madagascar identified by Boumans et al. (2007), referred to throughout the text.

FIGURE 57. Mantidactylus tricinctus in life, in dorsolateral and ventral view. (a,b) Adult male (not assignable to a voucher number; voucher probably deposited in UADBA) from Manombo Special Reserve, photographed in 2007.

FIGURE 58. Audiospectrogram and corresponding oscillogram of a 1000 ms section of a series of advertisement calls (8 calls figured) of Mantidactylus tricinctus, recorded on 23 February 2007 at Manombo (air temperature estimated at 25°C). Recording bandpass-filtered at 1200–7600 Hz.