Amphisbaena albocingulata

Description. (Figure 11 A – C) Slim, small-sized species. Snout-vent length 121.0 – 138.0 mm (mean = 130.2 mm; SD = 8.5; n = 4), caudal length 15.9 – 19.6 mm (mean = 18.0 mm; SD = 1.8; n = 3). Total length 140.9 – 156.6 mm (mean = 151.3 mm; SD = 8.9; n = 3). Head elongated, representing 3.3 – 3.6 % of snout-vent length (mean = 3.4; SD = 0.1; n = 4). Rostral shield triangular, barely visible in dorsal view, contacting first supralabial latero-posteriorly and nasals posteriorly. One pair of quadrangular nasal shields, together with rostral, constituting anterior face of snout. Suture between nasal shields representing 15.0 – 19.8 % of head length (mean = 17.4; SD = 2.0; n = 4). Nasal shields contact the first supralabials laterally and prefrontals posteriorly. Nostrils placed in the antero-lateral portion of shields. One pair of prefrontal shields enlarged, representing 32.9 – 34.6 % of head length (mean = 33.7; SD = 0.7; n = 4) and 35.4 – 38.6 % of head width (mean = 36.8; SD = 1.6; n = 4); prefrontal contacting second supralabial and ocular shield laterally and frontals posteriorly. One pair of frontal shields small, representing 27.6 – 32.1 % of head length (mean = 30.2; SD = 2.0; n = 4) and 26.4 – 30.3 % of head width (mean = 27.5; SD = 1.9; n = 4); frontal contacting postocular shields and dorsal angle of ocular shields laterally and parietals posteriorly. Eight parietal shields, centrals being pentagonal, with length equivalent to frontal shields (frontal length: mean = 0.9 mm; SD = 0.05; parietal length: mean = 1.1 mm; SD = 0.03). Other parietal shields quadrangular, contacting postocular and postlabial shields anteriorly, and occipital row posteriorly. Widened and quadrangular occipital shields, having different shape compared to body shields. Ocular shield rhomboid, contacting postocular posteriorly, and second and third supralabials ventrally. Postocular with similar size of ocular shields (postocular length: mean = 1.1 mm; SD = 0.04; postocular width: mean = 0.9 mm; SD = 0.09; ocular legth: mean = 1.2 mm; SD = 0.09; ocular width: mean = 0.9 mm; SD = 0.08). Temporal quadrangular, small, contacting postlabials shield in latero-ventral portion and third supralabial anteriorly. Ventral line sequence of shields comprise postocular, temporal and postlabial, forming first body annulus. Three supralabial shields. First triangular and smaller than others. Second and third higher than first, second having width similar to the first. Third shield pentagonal, wider than others, contacting postlabial posteriorly. Three infralabial shields. First quadrangular, contacting mental and postmental laterally, and second infralabial posteriorly. Second infralabial being wider and higher than others, contacting postmental and malar laterally, and third infralabial posteriorly. Third infralabial elongated and rectangular, as long as wide, contacting malar laterally and first body annulus posteriorly. Mental shield trapezoidal, small, representing 24.2 – 27.9 % of ventral head length (mean = 26.7; SD = 2.1; n = 3), contacting postmental shield posteriorly. Postmental shield elongated and heptagonal, representing 41.4 – 45.1 % of ventral head length (mean = 43.4; SD = 1.9; n = 3), contacting postgenial shields posteriorly. Presence of one or two rows of postgenial shields. The first postgenial row composed by two to three diamond-shaped shields. Second row of postgenial shields composed by three or four small, rounded shields, contacting laterally malar shields. One pair of malar shields trapezoidal, with internal line 39.8 – 54.6 % longer than external line (mean = 46.1; SD = 7.7; n = 3), contacting first body annulus posteriorly. Postmalars row absent, replaced by the first body annuli. Body annuli 190 – 204 (mean = 197.8; SD = 5.5; n = 5). Lateral sulcus visible from 20 th body annulus to cloacal shields. Dorsal segments of midbody annulus 12 – 14 (mean = 12.5; SD = 1.0; n = 4). Ventral segments of midbody annulus 16 – 18 (mean = 17.7; SD = 1.3; n = 4), centrals being wider than others. Caudal annuli 24 – 27 (mean = 25.5; SD = 1.3; n = 4), caudal autotomy plan evident on the eighth or ninth annulus. Segments from tip of the tail plain. Segments of fourth caudal annulus 22 – 25 (mean = 23.8; SD = 1.5; n = 3). Four precloacal pores, sequentially arranged in posterior portion of the last ventral annulus. Cloacal shield with 6 – 7 precloacal scales and 9 – 10 postcloacal scales. Colouration. Preserved specimens have nearly uniform pale brown colouration. Dorsally, brown colour increases slightly in intensity from head to tail. Ventrally, brown colouration more intense laterally, becoming faint on the mid-ventral line and head. On the tail, the colouration becomes darker. The cloacal shield may or may not be brown pigmented. Pigmentation uniform on each shields.

Diagnosis. Amphisbaena albocingulata is distinguished from other Amphisbaena species by the following combination of characters: (1) rounded snout; (2) nasal shields in contact on the dorsal portion of head; (3) caudal autotomy externally visible; (4) plain segments in the tip of the tail; (5) four precloacal pores; (6) 3 / 3 supralabial and 3 / 3 infralabial shields; (7) 190 – 204 body annuli; (8) 24 – 27 caudal annuli; (9) 12 – 14 dorsal and 16 – 18 ventral segments in the midbody annulus; (10) absence of the postmalar row. Comparison. Amphisbaena albocingulata can be distinguished from the species in the A. darwini complex, except from A. nigricauda, mainly by the absence of the posmalar row (vs. presence of posmalar row). It is distinguished from A. nigricauda by having 190 – 204 body annuli (vs. 222 – 226 body annuli). Differs from the species formerly considered belonging to the genus Anops by having a rounded-head (vs. keeled-head). Differs from A. angustifrons by having caudal autotomy (vs. lacking of caudal autotomy). Differs from A. leeseri by having four precloacal pores (vs. two precloacal pores). Differs from A. trachura by having plain segments in the tip of the tail (vs. tuberculated segments). Differ from A. heterozonata by having 19 – 24 caudal anulli (vs. 15 – 18 caudal anulli). Differ from A. hogei by having 24 – 27 caudal anulli (vs. 15 – 19 caudal annuli). Differs from A. munoai by having the anterior portion of the head smooth (vs. concavity in the anterior portion of the head) and squared-shaped frontal shields when considered together (vs. diamond-shaped). Differs from A. darwini by having frontal and parietal shields with similar size (vs. frontal shields much larger than parietal shields). It also differs from A. prunicolor by having ventral uniform brown colouration pattern (vs. venter light checkerboard colouration pattern).

Comments. On the original description of Amphisbaena albocingulata, Boettger (1885) suggested that the specimen could be a juvenile of A. darwini. The author referred to it as a new species because it presents a preocular shield on the left side of the head and two pairs of frontonasorostrals shields. In the present study, we considered the left preocular shield as an individual variation, because other variations in shape and number of shields on the left side of the specimen were observed. Besides, the preocular shield was not observed in any other specimen analysed. Additionally, on the species description, it was defined that both pairs of frontonasorostrals observed on the holotype would be equivalent in shape and size to the single pair present in A. darwini. Analysing head scutellation of A. albocingulata, we consider the term frontonasorostral as a synonym of prefrontal, which is the nomenclature currently in use. We observed that the first pair of shields, which the author refers to in the holotype, doesn’t represent two complete shields once their sutures do not meet at the centre of the head. Based on this observation, we considered the presence of only one pair of prefrontals (= frontonasorostral). The holotype has no cuts in the ventral body region, indicating that there was an analysis of the gonads and there is no record in the literature on age and sex of the specimen.

Distribution. Distributed in Paraguay, in Central and Paraguari departments (Figure 12). Gans (1966) provide photographies of the specimen registered to Asunción (MZUT 985 — Museo di Zoologia della Università di Torino, Italy), allowing its identification as Amphisbaena albocingulata. The records for Rio Apa (IMZUT 964 A – 964 C), the northern portion of the distribution in Paraguay, could not be confirmed because we cannot examine the voucher specimens. Gans (1966) recorded a specimen of Amphisbaena albocingulata from his private collection (GC 2808) to Brasília, Distrito Federal, Brazil. However, the author has indicated, in the same study, that the veracity of this record is uncertain. Currently this specimen is deposited in the Field Museum of Natural History in Chicago, United States (FMNH 264994), and the voucher data says ‘ 1963, Gift of zoo’. Considering the uncertainty about the record, the distance from the locality to others and the lack of subsequent records of this species in the vicinity, we suggest that the record of Amphisbaena albocingulata to Brasília might be an error of precedence of the specimen. Therefore, the occurrence of the species in Brazil is not confirmed. Gans (1966) also registered a specimen of Amphisbaena albocingulata in the Museo Argentino de Ciencias Naturales “ Bernardino Rivadavia ” (MACN 17840). This specimen was analysed in the present study and reidentified as Amphisbaena heterozonata. This were the only record of A. albocingulata from Argentina.

Holotype. ZISP 6660 (former ZIL or ZIN 6660; Figure 10) from Paraguay, without precise data collection, collected by H. Rohde (specimen examined by photographies). Specimen in good condition. According to Boettger (1885): total length 81 mm; tail length 10 mm; head length 4 mm; body annuli 190; caudal annuli 27. Uniform light brown body colouration.