Amerotyphlops montanum, Graboski & Arredondo & Grazziotin & Guerra-Fuentes & Da Silva & Prudente & Pinto & Rodrigues & Bonatto & Zaher, 2023

Graboski, Roberta, Arredondo, Juan C., Grazziotin, Felipe G., Guerra-Fuentes, Ricardo Arturo, Da Silva, Ariane A. A., Prudente, Ana L. C., Pinto, Roberta R., Rodrigues, Miguel T., Bonatto, Sandro L. & Zaher, Hussam, 2023, Revealing the cryptic diversity of the widespread and poorly known South American blind snake genus Amerotyphlops (Typhlopidae: Scolecophidia) through integrative taxonomy, Zoological Journal of the Linnean Society 197, pp. 719-751 : 731-735

AMEROTYPHLOPS MONTANUM SP. NOV.

( FIG. 11 ; SUPPORTING INFORMATION, FIG. S4 )

Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: BDB85DE5-C88C-4894-9197-60C3200FEC73

Holotype: An adult female, MZUSP 20065 , (field number MTR 16379 ), collected by Augustín Camacho, José Cassimiro, Mauro Teixeira Jr., Miguel T. Rodrigues, Renata C. Amaro and Renato Recoder 6 March 2009 from Parque Nacional Serra das Lontras (15° 11 ′ 46.32 ′′ S, 39° 20 ′ 54.24 ′′ W; c. 234 m a.s.l.), municipality of Arataca , state of Bahia, Brazil ( Fig. 11 ; Supporting Information, Fig. S4 ).

Diagnosis: This species is distinguished from all other South American congeneric species by a unique combination of the following of characters: (1) nasal suture incomplete; (2) rostral scale oval; (3) supralabial scales four; (4) infralabial scales three; (5) rows scales around the body 20/20/18; (6) mid-dorsal scales 220; (7) ventral scales 217; (8) rows of dorsal scales dark brown 11; (9) rows of ventral scales yellowish cream and immaculate 7–9; (10) caudal spine dark brown; (11) subcaudal scales 11; (12) TTL 216 mm; (13) TL 5.32 mm; (14) contact between the nasal process of premaxilla and vertical laminae of the nasals restricted to the anterodorsal portion, with the central and posteroventral portions not in contact, leaving a large canal between the olfactory chambers; (15) smallsized palatine fossa on the lateral side of the maxilla; (16) maxilla with a straight medial border; (17) ventral pterygoid process of palatine straight; (18) ratio between length of ventral pterygoid process of palatine and skull length 0.06; (19) angle between mandibular condyle articulation and the retroarticular process of the compound bone close to 90°; and (20) dorsal surface of dentary bone without evident foramina.

Amerotyphlops montanum differs from A. costaricensis , A. lehneri , A. microstomus , A. stadelmani , A. tasymicris , A. tenuis , A. trinitatus and A. tycherus by having an incomplete nasal suture (vs. complete nasal suture); from A. arenensis , A. caetanoi , A. amoipira , A. minuisquamus , A. paucisquamus and A. yonenagae by having20/20/18rowsscalesaroundthebody (vs.18/16/14, 18/18/14, 20/18/14 or 20/18/ 15 in A. minuisquamus and 18/18/ 18 in A. arenensis , A. caetanoi , A. amoipira , A. paucisquamus and A. yonenagae ); from A. reticulatus by having highly pigmented cephalic scales with a dark brown dorsum and dorsum tail brown (vs. yellow and few pigmented cephalic scales, dorsum brown or black and dorsum tail black with cream or yellow spot); and from A. brongermianus by having a larger interorbital relative width (INORB/HWE) 0.725 mm (vs. smaller interorbital relative width, between 0.526 –0.705 mm). Table 1 shows additional morphometric characters and scale patterns found in A. montanum and in a morphologically similar species distributed in southeastern Brazil ( A. brongermianus ).

Description of the holotype: Adult female, TTL 216 mm, TL 5.32 mm, MBD/(SVL-HR) 0.034 mm and TL/SVL 39.60 mm. Head slightly depressed dorsoventrally, not wider than ‘neck’. Snout round in dorsal and ventral views. Rostral oval, longer than wide, narrow at anteroposterior region and wider at medial region; visible in dorsal view, extending ventrodorsally without reaching the imaginary transverse line between anterior borders of eyes. Rostral contacting nasal (anterior and posterior) dorsolaterally, and first supralabial and anterior nasal scales ventrally. Nasal suture incomplete, only partially dividing the anterior and posterior portions of nasal scale. Suture begins in the upper edge of second supralabial, passes through nostril, but fails to reach rostral. Anterior nasal in contact with first infralabial and upper edge of second infralabial. Posterior nasal longer than wide, contacting upper margin of second supralabial and preocular. Supralabials four, fourth twice longer than third. Infralabials three, third largest. Eye diameter 1.03 mm; eyes not visible in ventral view, located dorsolaterally, close to suture between preocular and ocular scales, completely covered by ocular scale. Ocular scales contacting frontal. Body cylindrical and robust. Midbody diameter 7.12 mm. Dorsal and ventral scales cycloid, wider than long, highly imbricated and arranged in diagonal series; scale rows around the body 20/20/18. Mid-dorsal scales 220. Ventral scales 217. Cloacal plate rounded, bordered anteriorly by four rows of scales and posteriorly by five rows of scales. Subcaudal scales 11, excluding the terminal spine. Terminal spine large, stout base and dark brown.

Skull osteology (N = 1; MZUSP 20065): The length of the skull is 8.08 mm and the width is 4.14 mm. The snout region has a globular enlarged-shape and highly consolidated. The snout articulates with the braincase by the nasal and prefrontal sutures and with the frontal bone. The anteroventral region of the premaxilla has a short backward process.The midsagittal lamina separates both sides of the premaxilla ( Fig. 5 ). The lamina of the premaxilla is confluent with the mid-dorsal laminae of the nasals and with the mid-dorsal ridges of the vomeronasal cupola of the septomaxillae ( Fig. 5 ). The lamina of the premaxilla and the nasal laminae are restricted to the anterodorsal portion, with the central and posteroventral portions not in contact, leaving a large canal between the olfactory chambers ( Fig. 5A ). The medial side of the maxilla has a shallow depression (or fossa), where lodges the maxillary process of the palatine. The palatine fossa is on the lateral side of the maxilla, in the region of the articular fossa. The palatine fossa is small, with a diameter of 0.17 mm long ( Fig. 5B ). The medial border of the maxilla is straight ( Fig. 6B ). The ventral pterygoid process of the palatine is straight-shaped and ventrally directed ( Fig. 7A ). The retroarticular process projects in parallel to the horizontal plane of the articular. The angle between mandibular condyle articulation and the retroarticular process of the compound bone is close to 90° ( Fig. 8A ). The edentulous dentary is restricted to the distal end of the mandible, articulating mainly with the splenial. The dorsal side of the dentary is flat and without evident foramina ( Fig. 9B ).

Coloration of the holotype in preserƲatiƲe: Dorsum (11/11/11 rows scales) dark brown, venter (9/9/7 rows scales) yellowish cream (Supporting Information, Fig. S4A, B ). Dorsal portions of snout yellowish cream, with a dark brown spot, covering totally both rostral and nasal scales ( Fig. 11A, B ). Ventral portion of snout yellowish cream and few pigmented ( Fig. 11C ). Symphysial region yellowish cream and immaculate ( Fig. 11C ). Dorsal head scales (supraoculars, frontal, postfrontal, parietals and occipitals) and dorsal portions of lateral head scales (ocular, nasal and lower nasal) predominantly dark brown ( Fig. 11A, B ). Ventral portion of head scales (nasal and lower nasal) yellowish cream ( Fig. 11A, C ). Cloacal plate pale yellowish cream and terminal spine dark brown (Supporting Information, Fig. S4B ).

Etymology: The specific epithet is derived from the neutral form of Latin adjective ‘ montanus ’. It is a reference to the type locality, a high elevational forest, located on the slopes of a hill summit in the Brazilian state of Bahia.

Distribution and habitat: Amerotyphlops montanum is known from the Parque Nacional Serra das Lontras, situated at 10 km from the municipality of Arataca, in state of Bahia, Brazil, and from Reserva Particular do Patrimônio Natural Serra do Teimoso, situated at 5 km from the municipality of Jussari, in state of Bahia, Brazil ( Fig. 10B ).

These regions are known as part of the Serra das Lontras montane complex ( Nacif et al., 2009), belonging to the Atlantic Forest morphoclimatic domain, in the Bahia Coastal forest ecoregion ( Olson et al., 2001). The prevalent phytophysiognomy correspond to ombrophilous dense and semi-deciduous forests ( Veloso et al., 1991;Amorim & epiphytes, with a well-established and preserved understory. The forest changes dramatically above 800 m, presenting stunted trees (10–15 m tall), covered with small bromeliads, heavy bryophyte and lichen growth ( Veloso et al., 1991; Amorim & Matos, 2009; Reis & Fontoura, 2009). Additional data on the habitat of Serra das Lontras and Serra do Teimoso are, respectively, in Recoder et al. (2010) and Rodrigues et al. (2002).

Remarks: In our phylogenetic analysis we included a sample from a specimen from the Reserva Particular do Patrimônio Natural Serra do Teimoso, from the municipality of Jussari, in the state of Bahia, Brazil. Unfortunately, we did not have access to review this specimen, but we have recognized its molecular relationships with A. montanum . The tissue sample is currently stored in the genetic resource collection of Instituto de Biociências da Universidade de São Paulo University (see Supporting Information, Table S2).

Figures

Figure 4. Holotype of Amerotyphlops caetanoi sp. nov. (MZUSP S-023380). Head in left lateral (A), dorsal (B) and ventral (C) views. TTL = 176 mm. Scale bar equal to 5 mm.

Figure 5. Three-dimensional cutaway views along the sagittal axis of the nasal cavity in Amerotyphlops species based on HRXCT data. A, Amerotyphlops brongersmianus (MZUSP 14689); B, Amerotyphlops caetanoi sp. nov. (MZUSP S-023380). Insert show a lateral profile of the skull of A. brongersmianus presenting in red the position of the detailed region. Scales bars equal to 5 mm. Abbreviations: pmx, premaxilla; smx, septomaxilla; vm, vomer; na, nasal.

Figure 6. Three-dimensional reconstruction of the lateral region of the skull in Amerotyphlops species based on HRXCT data. A, Amerotyphlops caetanoi sp. nov. (MZUSP S-023380); B, Amerotyphlops montanum sp. nov. (MZUSP 20065); C, Amerotyphlops brongersmianus (MZUSP 14674). Insert shows a lateral profile of the skull of A. brongersmianus presenting in red the position of the detailed region. Scales bars equal to 5 mm.Abbreviations:mx, maxilla; mxpalf, palatine articulation fossa of the maxilla.

Figure 7. Three-dimensional reconstruction of the lateroventral region of the skull in Amerotyphlops species based on HRXCT data. A, Amerotyphlops caetanoi sp. nov. (MZUSP S-023380); B, Amerotyphlops brongersmianus (MZUSP 14674). Insert shows a lateral profile of the skull of A. brongersmianus presenting in red the position of the detailed region. Scales bars equal to 5 mm. Abbreviations: mx, maxilla; palmx, palatine maxillary process; palptv, palatine pterygoid ventral process; pt, pterygoid.

Figure 8. Three-dimensional reconstruction of the posterior region of the left mandible in Amerotyphlops speciesbased on HRXCTdata.A,Amerotyphlops caetanoisp. nov. (MZUSP S-023380); B, Amerotyphlops brongersmianus (MZUSP 14674). Insert shows a lateral profile of the skull of A. brongersmianus presenting in red the position of the detailed region. Scales bars equal to 5 mm. Abbreviations: cb, compound bone; q, quadrate; rp, retroarticular process.

Figure 9. Three-dimensional reconstruction of the anterior region of the left mandible in Amerotyphlops species based on HRXCT data. A, Amerotyphlops caetanoi sp. nov. (MZUSP S-023380); B, Amerotyphlops montanum sp. nov. (MZUSP 20065). Insert shows a lateral profile of the skull of A. brongersmianus presenting in red the position of the detailed region. Scales bars equal to 5 mm. Abbreviations: cb, compound bone; co, coronoid; d, dentary; sp, splenial.

Figure 10. Geographical distribution of nine species belonging to the genus Amerotyphlops from South America.A, zoomed map of species distributed in the north-eastern Brazil; B, zoomed map of four new species described in this work. Symbols: A. arenensis (black pentagons); A. amoipira (black diamonds); A. brongersmianus (black circles); A. yonenagae (black squares); A. pauciquamus (black inverted triangles); A. martis sp. nov. (black star); A. montanum sp. nov. (black triangles); A. illusorium sp. nov. (black cross); Amerotyphlops caetanoi sp. nov. (black asterisk).

Figure 11. Holotype of Amerotyphlops montanum sp. nov. (MZUSP 20065). Head in left lateral (A), dorsal (B) and ventral (C) views. TTL = 216 mm. Scale bar equal to 5 mm.