Amerotyphlops caetanoi, 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 : 726-730

AMEROTYPHLOPS CAETANOI SP. NOV.

( FIG. 4 ; SUPPORTING INFORMATION, FIG. S3 )

Z o o b a n k r e g i s t r a t i o n: L S I D u r n:l s i d:z o o b a n k. org:act: BA5C7CBF-7391-4797-8CEC-DF201B294A73

Holotype: An adult female, MZUSP S-023380, (field number MTR 19921 ), collected by Ana C. Q. Carnaval, José C. Silva, Marco A. Sena, Mauro Teixeira Jr., Miguel T. Rodrigues, Renata C. Amaro and Renato Recoder on 15 December 2010 from Parque Nacional da Chapada Diamantina , on BR 144 Road, municipality Lençóis (12° 32 ′ 44.682 ′′ S, 41° 21 ′ 50.364 ′′ W; c. 493 m a.s.l.), state of Bahia, Brazil ( Fig. 4 ; Supporting Information, Fig. S3 ).

Diagnosis: This species is distinguished from all other congeneric species by the 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 18/18/18; (6) mid-dorsal scales 212; (7) ventral scales 202; (8) rows of dorsal scales dark brown 13; (9) rows of ventral scales yellowish cream and immaculate 5; (10) caudal spine dark brown; (11) subcaudal scales 9; (12) TTL 176 mm; (13) TL 4.33 mm; (14) broad contact between the lamina of the premaxilla and the vertical laminae of the nasals, forming a continuous bony septum separating the olfactory chambers; (15) large 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 0.25; (19) angle between mandibular condyle articulation and the retroarticular process of the compound bone close to 90°; and (20) dorsal surface of dentary bone with two evident foramina.

The new species differs from Amerotyphlops 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. brongersmianus , A. reticulatus and A. minuisquamus by having 18/18/18 rows scales around the body (vs. 18/16/14, 18/18/14, 20/18/14 or 20/18/ 15 in A. minuisquamus ; 20/20/18 or 20/20/ 20 in A. brongersmianus and A. reticulatus ); from A. brongersmianus by having an angle close to 90° between mandibular condyle articulation and the retroarticular process of the compound bone (vs. an angle of 135°); from A. yonenagae by having less than 250 mid-dorsal scales (vs. more than 250 mid-dorsal); from A. amoipira by having highly pigmented cephalic scales with a dark brown dorsum (vs. few pigmented cephalic scales, creamy brown dorsum with a fine darker brown paravertebral line concentrated in the anterior part of the body); from A. paucisquamus by having a largest number of mid-dorsal, 212 (vs. fewer number of mid-dorsal, between 162 and 209); and from A. arenensis by having a smaller rostral width (RW1) at dorsal portion, 1.29 mm (vs. larger rostral width at dorsal portion (RW1), between 1.44 and 2.13 mm). Table 1 shows additional morphometric characters and scale patterns found in A. caetanoi and morphologically similar species distributed in southern and north-eastern Brazil.

Description of the holotype: Adult female, TTL 176 mm, TL 4.33 mm, MBD/(SVL-HR) 0.036 mm, and TL/SVL 39.72 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 0.56 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 6.21 mm. Dorsal and ventral scales cycloid, wider than long, highly imbricated and arranged in diagonal series; scale rows around the body 18/18/18. Mid-dorsal scales 212. Ventral scales 202. Cloacal plate rounded, bordered anteriorly by four rows of scales and posteriorly by five rows of scales. Subcaudal scales nine, excluding the terminal spine. Terminal spine large, stout base and dark brown.

Abbreviations: ED, eye diameter; HR, head radius; HWE, head width; IN, internasal distance; INORB, interorbital distance; RL, rostral length; RW1, rostral width; MBD, midbody diameter.

Skull osteology (N = 1; MZUSP S-023380): The length of the skull is 6.15 mm, the width is 2.92 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 in contact, forming a continuous bony septum separating the olfactory chambers ( Fig. 5B ). 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 large with a diameter of 0.25 mm long ( Fig. 6A ). The medial border of the maxilla is straight ( Fig. 6A ). The ventral pterygoid process of the palatine is straight 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 pierced by two foramina ( Fig. 9A ).

Coloration of the holotype in preserƲatiƲe: Dorsum (13/13/13 row scales) dark brown (Supporting Information, Fig. S3A ), venter (5/5/5 rows scales) yellowish cream (Supporting Information, Fig. S3B ). Dorsal portions of snout yellowish cream, with a dark brown spot, covering both rostral and nasal scales (two-thirds of snout) ( Fig. 4A, B ). Ventral portions of snout yellowish cream and few pigmented ( Fig. 4C ). Symphysial region yellowish cream and immaculate ( Fig. 4C ). Dorsal head scales (supraoculars, frontal, postfrontal, parietals and occipitals) dark brown. Dorsal portions of lateral head scales (ocular, nasal and lower nasal) and ventral portions yellowish cream with dark brown spots. Cloacal plate pale yellowish cream and terminal spine dark brown ( Fig. 4A–C ).

Etymology: The name is a homage to Brazilian composer, singer and political activist Caetano Emanuel Viana Telles Veloso, better known as Caetano Veloso. Caetano is one of the most famous Brazilians born in the state of Bahia (in 1942), the same state in which the new species occurs. He became known for his participation in the Brazilian musical movement ‘ Tropicalismo ’ that encompassed theatre, poetry and music in the 1960s, at the beginning of the Brazilian military dictatorship. Veloso is also a well-known conservationist, acting to give voice to the preservation of the Brazilian natural environments and to indigenous resilience.

Distribution and habitat: Amerotyphlops caetanoi is known only from Parque Nacional da Chapada Diamantina, in the BR 144 Road, situated at 2 km from the municipality of Lençóis, state of Bahia, Brazil ( Fig. 10B ). This region is one of the largest upland Atlantic dry forest enclaves of the east-central Bahia state ( Veloso et al., 1991). The phytophysiognomy corresponds to a submontane seasonal semi-deciduous forest ( Couto et al., 2011; Braz et al., 2013), ranging from 400 to 600 m a.s.l., with an annual average of temperature and rainfall of 20 °C and 100 mm, respectively ( Funch et al., 2009). This area presents a non-continuous canopy, consisting of tall trees (approximately 10–16 m), and a subcanopy, consisting of medium-height trees (approximately 6–9 m), with a well-established and preserved understory ( Couto et al., 2011).

Figures

Figure 3. Results of partial least square discriminant analysis (PLS-DA) and linear discriminant analysis (LDA). A, PLS-DA of the simulated dataset based on seven discrete (pholidosis) and 14 rates characters for five OTUs (Group 1). B, PLS-DA of the simulated dataset based on seven discrete (pholidosis) and 14 rates characters for four OTUs (Group 2). C, LDA of the simulated dataset based on 15 continuous (linear morphometrics) characters for five OTUs (Group 1). D, LDA of the simulated dataset based on 15 continuous (linear morphometrics) characters for four OTUs (Group 2). Species are colour-coded according to OTUs (see Key-colour OTUs, on the bottom).

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).