Rediscovery of Phalotris concolor ( Serpentes : Dipsadidae : Elapomorphini )

Phalotris concolor Ferrarezzi, 1994 is a poorly known species described on the basis of a single female from municipality of Cristalia, state of Minas Gerais, Brazil. Based on two recently collected specimens, we expand the knowledge of P. concolor with new morphological data, including the description of its hemipenis and color in life. A summary of comparative data between species of the P. nasutus group is present to aid the identification of new specimens. The new findings are important for a better understanding of the taxonomy of Phalotris.

Phalotris Cope, 1862 comprises 13 species of small to medium-sized fossorial snakes, which are widely distributed in open areas from Central Brazil to Argentina (PUORTO & FERRAREZZI 1994, LEMA 2002, JANSEN & KÖHLER 2008).Phalotris is distinguished from other Elapomorphini genera (Apostolepis Cope, 1862, Coronelaps Lema, 2010, andElapomorphus Wiegman, 1843) by having fused prefrontals, which are separated from internasals.This genus is currently divided into three species groups: P. tricolor, P. bilineatus, and P. nasutus (FERRAREZZI 1994).The Phalotris nasutus group is diagnosed by two synapomorphies: a pointed snout with prominent rostral shield and fusion between the second and third series of temporal plates (sometimes on only one side of the head) (FERRAREZZI 1994).This group includes five valid species: P. concolor Ferrarezzi, 1994, P. labiomaculatus Lema, 2002, P. lativittatus Ferrarezzi, 1994, P. nasutus (Gomes, 1915) and P. nigrilatus Ferrarezzi, 1994(FERRAREZZI 1994, LEMA 2002).FERRAREZZI (1994) described P. concolor on the basis of a single female.Up to now, this species was known only from the holotype and diagnosed by characters such as the presence of an anterior temporal shield, lower and upper postoculars similar in size, 224 ventrals, and uniform dorsal coloration (FERRAREZZI 1994).In this study, we provide new data on morphological variation (meristic, morphometric, color pattern, hemipenial morphology) of P. concolor based on two additional specimens.

MATERIAL AND METHODS
We collected two specimens of Phalotris concolor during fieldwork carried out in the municipalities of Brasilândia de Minas and Urucuia, northwestern Minas Gerais State, Brazil (Figs 1-8).The snakes were captured in pitfall traps (60 L) with drift fences set in a riparian zone (habitat details in Discussion).Specimens were euthanized using an intra-peritoneal injection of 2% Xylocaine, fixed in 10% formalin, preserved in 70% ethanol and deposited in the herpetological collection of the Museu de Zoologia João Moojen, Universidade Federal de Viçosa (MZUFV), Viçosa, Minas Gerais (numbers MZUFV1870 and MZUFV1890).
Terminology follows PETERS (1964) for scale counts and cephalic shields, except for temporal shields, which follows FERRAREZZI (1994).We obtained the following measurements in millimeters: snout-vent length (SVL); tail length (TL); head length (HL, from tip of the snout to the retroarticular process of the mandible); greatest head width (HW); internasal distance (ID, head width between the nares); horizontal eye diameter (ED); eye-nostril distance (END, from the anterior edge of the eye).
Measurements (length/width) of the cephalic shields follow CACCIALI et al. (2007).The "anterior gulars" and "posterior gulars" of CACCIALI et al. (2007) here are named "anterior chinshields" and "posterior chinshields", following PETERS (1964).The "temporal" measurement of CACCIALI et al. (2007) was expanded to "anterior temporal" and "posterior temporal", since the species studied by them (P.nigrilatus) exhibits only one series of temporal shield.The SVL and TL were measured with a flexible ruler to the nearest 1.0 mm and HW was measured with a digital caliper to the nearest 0.1 mm, whereas all other measurements were obtained under a stereomicroscope with millimetric ocular to the nearest 0.1 mm.

TAXONOMY
Phalotris concolor Ferrarezzi, 1994 Phalotris concolor Ferrarezzi, 1994. Memórias do Instituto Butantan, vol. 55  Emended diagnosis.Phalotris concolor can be diagnosed by the following combination of characters: 15-15-15 smooth dorsal scale rows, without apical pits; temporal formula 1+1 (1+1+1 in one side of the head of the holotype); pointed snout with prominent rostral shield; internasal suture absent (n=1) or present (n=2); lower postocular reduced in size; six supralabials, the second and third contacting the eye; seven infralabials, the first four contacting the first pair of chinshields; 212 ventrals in the known male, 220-224 in females; 34 divided subcaudals in the male, 28-29 in females; cloacal shield divided; head dark brown above and ventrally cream; body red, reddish orange or light brown on the dorsum, and uniform cream ventrally; light nuchal collar three scales wide, and dark neck collar 2-3 scales wide.Hemipenis deeply bilobed.Table I shows a summary of morphometric and meristic data of P. concolor.
Comparisons with other species of the nasutus group.Phalotris concolor can be distinguished from P. lativittatus, P. nasustus and P. nigrilatus by having more than 200 ventrals in males and more than 210 ventrals in females.It can be distinguished from P. labiomaculatus (characters inside brackets) by having seven infralabials (eight) and supralabials mainly creamish (cream with black blotches).Table II shows a summary of comparative data between species of P. nasutus group.
Color in life.Dorsum of head dark brown, supralabials cream; a black spot (faint in MZUFV1890) on the lower margin of first supralabial; upper margins of second to fourth supralabials dark brown, and upper half or more of the fifth and sixth supralabials dark brown.A pale orange or cream nuchal collar, three dorsal scales wide, behind parietals, followed by a black, brownish gray or brown nuchal collar two dorsal scales wide beginning at the fourth dorsal scale row (Figs 5 and 6).Head ventrally cream, except for dark brown marks on rostral, mental, inner margins of first and fourth infralabials and first pair of chinshields.In MZUFV 1870, dark markings also present in center of fifth infralabial (Figs 7 and 8).Dorsal scale rows 1-3 pale orange (MZUFV 1870) or cream (MZUFV 1890); above fourth scale row dorsum becomes reddish orange (MZUFV 1870) or light brown (MZUFV 1890).Faint (almost invisible) dark lateral line present on posterior portion of body of MZUFV 1870, between third and fourth scale rows; dark lateral line (faint in MZUFV 1890) present along second scale row of tail.Venter cream.In preservative, dorsal body color and nuchal collar become cream or whitish.
Hemipenis (MZUFV 1890).Description based on the fully everted and expanded right organ, extracted from the preserved specimen.Hemipenis deeply bilobed, semicalyculate, semicapitate.Total length 15.6 mm, lobe length 7.2 mm.Lobes with papillate calyces; larger calyces present on asulcate and medial surface of lobes, and also on distal region of asulcate side of hemipenial body.Hemipenial body with spinules on sulcate side.Asulcate side almost naked, except for some large spinules below lobes, converging into narrow median longitudinal row proximally.Lateral sides with two longitudinal rows of spines, one closer to asulcate and another closer to sulcate side.Row closer to asulcate side composed by three large spines decreasing in size proximally (the most distal spines are slightly curved distally).Row closer to sulcate side with four or five smaller spines, decreasing in size proximally.Four additional small spines present on both lateral sides, between the two rows of larger spines .
Distribution.Phalotris concolor is known from three localities associated with the Tropical and Subtropical Savannas ecoregion (OLSON et al. 2001), in areas represented by the Cerrado morphoclimatical domain in the northern part of Minas Gerais (Fig. 13).

DISCUSSION
In most specimens of the Phalotris nasutus group, the second and third temporals are fused into a large shield (FERRAREZZI 1994).In the holotype of P. concolor, the second and third temporal on the left side are not fused (FERRAREZZI 1994).Regardless of this asymmetry, it is worth noting that P. concolor has a temporal formula of 1+1, in contrast with the 0+1 pattern in the remaining species of the nasutus group with the exception of P. labiomaculatus (see Table II).
While the holotype (FERRAREZZI 1994) and MZUFV 1890 have an anterior temporal plate separating the fifth supralabial from the parietal, MZUFV 1870 has reduced anterior temporals on both sides of the head (Table I).Because of this reduced anterior temporal, the lower postoculars of MZUFV 1870 contact the third, fourth and fifth supralabials, instead of only the third and fourth, and its anterior and posterior temporals are separated by the fifth supralabial.Polymorphism related to temporal shields has been reported for other Elapomorphini such as Apostolepis cearensis Gomes, 1915(FERRAREZZI et al. 2005), Apostolepis nigrolineata (Peters, 1869)  When alive, the dorsal color of the two known females of P. concolor (IBSP 55018 and MZUFV 1870) is uniformly red (FERRAREZZI 1994) or reddish orange, while the male (MZUFV 1890) is light brown, and the dark lateral line on the tail is almost invisible.These differences could be due to sexual dichromatism (e.g., SHINE 1993, PIZZATTO et al. 2007) or simply a polymorphism.
Secondary sexual dimorphism is also found in scale counts, with females having more ventrals (220 and 224), fewer subcaudal pairs (28 and 29) and shorter tails in proportion to their body length (ratios: 0.071 and 0.078), when compared with the only known male (212 ventrals, 34 subcaudals and tail/body length ratio 0.103).These are common features in snakes (GREENE 1997), already reported for the Phalotris nasutus group (FERRAREZZI 1994).
Although P. concolor is considered the most basal lineage within P. nasutus species group on the basis of meristic characters (FERRAREZZI 1994), hemipenial morphology may offer contradictory evidence.The deeply bilobed hemipenis of P. concolor is more similar to the hemipenis of P. labiomaculatus (LEMA 2002) and P. nigrilatus (CACCIALI et al. 2007) than of P. nasutus and P. lativittatus (FERRAREZZI 1994, ZAHER 1999).Hemipenial spines of P. concolor seem to be the smallest of all within nasutus group.The curvature in the largest spines of P. nigrilatus was considered an autapomorphy (CACCIALI et al. 2007), but this character is also present in P. concolor, although only in the largest lateral spines closer to the asulcate side.
Three corrections on the type locality of P. concolor must be made: I) the spelling of the river on whose bank the holo-   FERRAREZZI (1994) considered P. concolor to be restricted to the eastern part of the Espinhaço mountain range, separated from the geographically closest species (P.nasutus) by an extensive area occupied by the São Francisco River basin.The collection of two new specimens from the São Francisco River basin suggests that the distribution range of P. concolor is greater than previously thought.A fourth, unconfirmed record of P. Frontal -2.5 x 2.1 (3.2 x 3.0 Supraoculars -1.6 x 0.8/1.6 x 0.8 1.9 x 1.1/1.9x 1.1 Parietals -4.8 x 2.4/4.9 x 2.3 5.7 x 3.0/5.5 x 2.8 Preoculars -1.0 x 0.8/0.9x 0.8 1.3 x 1.0/1.2x 1.0 Upper postoculars -0.6 x 0.6/0.6 x 0.6 1.1 x 1.0/0.9x 1.0 Lower postoculars -0.5 x 0.7/0.6 x 0.7 0.6 x 0.6/0.7 x 0.5 Anterior temporals -1.2 x 0.5/0.8x 0.4 2.7 x 0.9/2.4(2002), data of P. concolor are present as of P. nasutus, data of P. nasutus are present as of P. lativittatus, and data of P. lativittatus are present as of P. concolor.† The upper occipital shield used by LEMA ( 2002) is here considered as the third temporal shield, following FERRAREZZI (1994).
There are no confirmed records of P. concolor in legally protected areas, and the type locality is within a priority region (Espinhaço Norte) for herpetofauna conservation in Minas Gerais (DRUMMOND et al. 2005).The lack of information about this species has led to its classification as Data Deficient (MAR-TINS et al. 2008).Studies have shown that the upland areas around aquatic environments are important for wildlife conservation (SEMLITSCH & BODIE 2003, FRAGA et al. 2011).The two specimens of P. concolor reported herein were captured in riparian vegetation.The holotype also seems to have been collected in a riparian zone, on the bank of Itacambiruçu River.Therefore, it is possible that P. concolor prefers riparian habitats, which emphasizes the importance of these areas for the conservation of the species.

Table I .
FERRAREZZI (1994)metric and meristic data of known specimens of Phalotris concolor.Holotype data are based on the text and illustrations provided byFERRAREZZI (1994).All measures are in millimeters.A slash (/) is used to indicate the left and right sides, respectively, when they differ in some feature.Shield sizes are represented as width x length.