Chironius flavolineatus ( Jan, 1863 )

Hamdan, Breno & Fernandes, Daniel S., 2015, Taxonomic revision of Chironius flavolineatus (Jan, 1863) with description of a new species (Serpentes: Colubridae), Zootaxa 4012 (1), pp. 97-119 : 100-107

Chironius flavolineatus ( Jan, 1863)

Herpetodryas carinatus var. flavolineata: Jan 1863:80 .

Herpetodryas flavolineatus — Boettger 1885:234.

Herpetodryas carinatus var. flavolineata— Boettger 1898:55.

Chironius flavolineatus — Bailey 1955:13 [partim]; Peters & Orejas-Miranda 1970:60 [partim]; Dixon et al. 1993:112 [partim]; Hamdan et al. 2014:139.

Lectotype. Adult male, MSNM Re2729, from Brazil without specific locality (see Hamdan et al. 2014 for additional informations).

Diagnosis. Chironius flavolineatus can be distinguished from all congeners by the following unique combination of states of character: first third of body black or dark gray; vertebral stripe yellowish or creamish white, distinct from dorsals of nape and extending throughout almost whole body length; head dorsum tan to brown, distinct from background color of first third of body; posterior temporal scale one; cloacal shield divided; maximum of two rows of keeled dorsal scales at midbody; ventral ground color completely creamish white or yellowish without ornamentation; dark longitudinal stripes (in “zigzag”) along midventral portion of subcaudals absent; hemipenis with no spinules separating calyces of apex from spines below region of constriction on asulcate side; sulcus spermaticus positioned on concave face of hemipenis in lateral view; ascending process of premaxilla perpendicular to longitudinal axis of skull; optic fenestra exceeding frontoparietal suture; posterior border of supratemporal not exceeding braincase; dorsoventral axis of quadrate straight, not moving away from longitudinal axis of skull.

Comparisons. Chironius flavolineatus is distinguished from all currently recognized congeners, except C. diamantina , by having first third of body black or dark gray, vertebral stripe yellowish or creamish white, distinct from dorsals of nape and extending throughout almost whole body length, and head dorsum tan to brown distinct from background color of first third of body. Chironius flavolineatus differs from Chironius diamantina (character states in parentheses) by having posterior temporals frequently one (vs. two to four); cloacal shield divided (vs. entire); number of rows of keeled dorsal scales at midbody 0–4 (vs. 6–10 rows of keeled dorsal scales at midbody); ventral and subcaudal scales creamish white without pigmentation (vs. ventral scales with dark edges forming conspicuous transverse bars virtually throughout whole belly and conspicuous dark longitudinal stripes in “zigzag” at midventral suture of subcaudals).

Color pattern variation in preservative (alcohol 70%, Fig. 1 ). Dorsum of head tan to brown, distinct from background color of first third of body, which is black or dark gray. A yellowish or creamish white vertebral stripe one scale wide, distinct from dorsals of nape and extending throughout almost whole body length, gradually fading around midbody where it merges into dorsal body coloration. Postocular region with no pigmentation (71%), with dark postocular spot (27%), or, most rarely, dark postocular stripe reaching postoculars, temporals, and last supralabials (2%). Ventral surface of head creamish white. Dorsal ground color of body brownish; dorsal scales may show whitish or black edges. Ventral ground color yellowish, occasionally with longitudinal lines (n = 145; 55%). Ontogenetic variation not detected with hatchlings showing the same color pattern of adults.

Color in life ( Fig. 2 ). General color of head, venter and body similar to preserved specimens (alcohol 70%). Some individuals have a reddish brown dorsum. No ontogenetic variation detected.

Meristic and morphometric variation. Largest male (MNRJ 10929) 738 mm SVL, 450 mm CL; largest female (MZUFV 1090) 880 mm SVL, 524 mm CL. Total length 405–1188 mm (n = 56) in males, 235–1404 mm (n = 86) in females; snout length 3.5–7.9 mm (n = 64) in males, 3.3–8.9 mm (n = 98) in females; snout width 3.3–7.1 mm (n = 64) in males, 2.9–7.9 mm (n = 98) in females; head length 13.4–25 mm (n = 67) in males, 12.0– 29.2 mm (n = 101) in females; head width 5.1–13.1 mm (n = 65) in males, 4.9–15.0 (n = 98) in females; body width at midbody 3.3–12.8 mm in males, 3.0– 16.7 mm (n = 102) in females; body height at midboby 2.9–13.7 mm (n = 64) in males, 3.2–18.5 mm (n = 100) in females. The number of occipitals contacting parietals 2–6 (x¯ = 4.1; s = 0.71; n = 106); gulars 3–4. Dorsal scales rows formulae 12/12/8 (n = 66; 93%) or 12/12/10 (n = 6; 7%) in males, and 12/ 12/10 (n = 109; 100%) in females, showing sexual dimorphism. Variation of other meristic and morphometric data for C. flavolineatus is summarized in Table 2.

Ornamentation of dorsal scales. Apical pits in adults generally restricted to neck (n = 28; 23%) or found at midbody and/or near cloacal region (n = 95; 77%). Neck with high density of apical pits, some specimens showing scales with two apical pits.

Hemipenis (n = 7, Fig. 3 ). Organ unilobed, cylindrical, and unicalyculate. Hemipenis with large spinulate and well developed calyces on most of the apical portion. Medial portion of hemipenis with constriction region with no spinules separating calyces of apex from spines below region of constriction on asulcate side. Medium to large curved spines covering lateral and asulcate sides and spinules covering sulcate side of hemipenis. Sulcus spermaticus simple, centrolineal, bordered by spinules along its extension, and positioned more laterally at basal portion of hemipenis, gathering more centralized position from the end of proximal third of hemipenis. In lateral view, sulcus spermaticus positioned on concave face of the organ. Basal portion of hemipenis with few spinules irregularly distributed.

Cephalic glands (n = 4, Fig. 4 ). PREMAXILAR: triangular, contacting supralabial gland and dorsally reaching the level of internasal scales. NASALS: irregular shape, ventrally higher than long, anteriorly limited by nasal capsule, anterodorsally by nasal, posteroventrally by anterior portion of prefrontal, and ventrally by supralabial gland; nasal gland reaches or surpasses dorsal edge of orbit in dorsal view. SUPRALABIALS: rear portion partially overlaid by Duvernoy gland and anterior end contacting premaxilar gland; posterior limit located ventrally to rear portion of postorbital lobe of Harder gland; supralabial glands contact part of the muscles adductor mandibulae externus medialis (hereafter aem) and adductor mandibulae externus profundus (hereafter aep). HARDER: postorbital lobe partially visible, dorsal portion partly covered by musculus adductor mandibulae externus superficialis (hereafter aes) and ventral portion contacting Duvernoy gland; laterally, after removal of muscle aes, postorbital lobe extends posteriorly to the level of muscle aep; dorsal edge reaches first third of orbital cavity, not reaching dorsal portion of parietal; orbital lobe with irregular dorsal edge, convex, occupying major portion of orbital cavity from its ventral edge; orbital and postorbital lobes about the same size. DUVERNOY: poorly developed, covering posterior portion of supralabial gland and the ventral limit of Harder gland, with no contact to adductor muscles of mandible; maximum height less than one third of height of orbital cavity. RICTAL: indistinct or absent. INFRALABIALS: elongated, rear limit contacting muscle aem and reaching about the same level of posterior limit of Duvernoy gland; infralabial glands with no anteromedial contact and mesoposterior portion slightly wider. MEDIAL SUBLINGUAL: elongated, anteriorly located between mesial portion of lateral sublingual glands, with rear limits about the level of posterior extremity of infralabial glands. LATERAL SUBLINGUAL: elipsoidal, diverging anteroposteriorly.

Skull (n = 5, Fig. 5 ). Rectangular in dorsal view, with constriction at level of frontals. Dorsal surface flat and smooth, except for occipital region with ridges and slope from posterior portion of supraoccipital. In lateral view, height of skull gradually rises to the level of frontals and become relatively flat from this region until the distal portion of skull. Ventrally, hemimandibles with arched shape slightly approach each other in the medial portion of skull. PREMAXILLA: triangular in frontal view, dorsal extremity of ascending process tapered with no contact to nasals; transverse processes oblique approaching maxillary bones and positioned slightly more anteriorly; short convergent vomerine processes forming a “V” anteroposteriorly, without contact each other, reaching anterior portion of vomer; total length of transverse processes greater than height of ascending process from base to apex. SEPTOMAXILLA: ascending lateral processes short, not reaching lateral extremities of nasals; medial portion contacts vertical lamina of nasals and ascending process of premaxilla, while rear portion contacts vomer. NASALS: triangular in dorsal view, base of triangle on the region of contact between nasals; anterior border tapered, not contacting premaxilla; nasals contact frontals through vertical lamina of nasals, which also contacts septomaxilla and vomer. VOMER: dorsally connected to septomaxilla; mesoventral portion of vomer globular with circular opening corresponding to exochoanal fenestra; in this portion, vomers approach each other in mesial region. PREFRONTALS: region of contact with frontals oblique; ventral portion contacts maxillary process and choanal process of palatine medially; in lateral view, prefrontals with conspicuous and acuminate anterior process; posterior portion concave, shaping anterior border of orbital cavity; in rear view, large lacrimal foramen visible in most basal portion. FRONTALS: dorsal surface smooth with medial suture separating the bones; lateral surface with conspicuous constriction; anterolateral edges oblique, projected, and contacting prefrontals; medial region of anterior margin “V” shaped; suture contacting parietal straight or slightly curved; posterolateral region, near suture with parietal, with 0–3 foramens; vertical lamina of frontals contacting dorsal projection of parabasisphenoid ventrally and nasals and septomaxilla anteriorly. PARIETAL: overall aspect rounded in dorsal view, as long as broad, with anterior margins concave or straight contacting frontals; lateral ridges visible in dorsal view, extending up to region of contact with supraoccipital; lateral ridges not touching each other; anteriormost portion contacts frontals lateroventrally and parabasisphenoid ventrally; rearmost portion of parietals contacts prootic and supratemporal posterolaterally. POSTORBITALS: shape rearward portion of orbital cavity and have no contact with frontals; straight in lateral view, with no ventral curvature and not approaching region of contact between ectopterygoid and maxilla. SUPRAOCCIPITAL: dorsally contacts parietal anteriorly through curved suture; supratemporal and prootic laterally, and exoccipital posteriorly; mesoanterior portion undergoes constriction relative to lateral regions; posterolateral region with two conspicuous and oblique ridges towards supratemporals; among these side crests emerges a rather pronounced medial ridge, restricted to posterior portion of supraoccipital, occasionally touching exoccipitals; this region shows a depression relative to anteriormost portion of supraoccipital. EXOCCIPITALS: irregular shape in dorsal view, showing medial constriction and two lateral ridges corresponding to maintenance of posterolateral ridges of supraoccipital; medially exoccipitals may show a rather conspicuous ridge representing maintenance of medial supraoccipital ridge; exoccipitals contact basioccipital ventrally and prootic in lateral surface, where is situated fenestrae ovalis, between supraoccipital and prootic; jugular foramen positioned just beneath this fenestra. BASIOCCIPITAL: hexagonal, contacting parabasisphenoid complex anteriorly, and prootic and exoccipitals in anterior and posterolateral portions, respectively; mesoanterior portion with three conspicuous (n = 4) or slightly distinct (n = 1) dentigerous processes, away from suture with parabasisphenoid. PROOTIC: contacts supratemporal dorsally, parietal anterolaterally, parabasisphenoid and basioccipital ventrally, supraoccipital dorsoposteriorly, and exoccipital posterolaterally; two lateral foramina represent maxillary and mandibular branches of trigeminal nerve; posterior edge of prootic contacts exocippital, constituting anterior margin of fenestrae ovalis. PARABASISPHENOID COMPLEX: spear shaped, with rear end broader than anterior portion tapering from the level of contact between ectopterygoid and maxilla; contacts basioccipital posteriorly, prootic and parietal posterodorsally, frontal dorsoanteriorly, and choanal process of palatine anteroventrally; posterior Vidian foramen near sutures with prootic and parietal in posterolateral region; basisphenoid with medial ridge, more conspicuous on the level of posterior boundary of orbital cavity. MAXILLAE: arched towards premaxilla in dorsal view, with a slight lateral twist on the level between prefrontal and ectopterygoid; laterally maxilla corresponds to inferior border of orbital cavity, extending from the level of premaxillary vomerine processes up to the level of postorbital, when contacts ectopterygoid; maxilla corresponds to more than half of length of braincase; ventral surface with 31˗35 subequal, curved, and rear facing teeth, with posterior teeth slightly larger and having no diastema; palatine process situated in first third of maxilla and completely covered by prefrontal; ectopterygoid process situated posteriorly. ECTOPTERYGOIDS: narrow, slightly curved, with anterior end in half moon shape, superimposed on ectopterygoid process of maxilla; rear end contacting dorsolateral portion of pterygoid. PTERYGOIDS: elongated, corresponding approximately to half size of braincase; ventral surface with 33–37 subequal teeth; anterior portion tapered contacting palatine and gradually widening from the region of contact with ectopterygoid in anteroposterior direction; pterygoids nearly parallel along its length, except in rear end, at the end of tooth line, from which pterygoids taper again and move apart until contact quadrate dorsolaterally. PALATINES: slender, straight, slightly shorter than length of dentary; ventral surface with 20–23 subequal teeth; choanal process of palatine medially directed towards parabasisphenoid, contacting small portion of ventromedial face of prefrontal; anterolateral process contacts palatine process of maxilla; in dorsal view, forked rear end contacts pterygoid, with medial branch longer than lateral branch; palatine contacts pterygoid approximately at the level of ectopterygoid process of maxilla. SUPRATEMPORALS: laminar shape, elongated, approximately same length of quadrate; anterior end contacts or surpasses suture with parietal; contacts prootic and exoccipital laterally; rear end articulates with quadrate. QUADRATES: dorsal portion flattened, contacting supratemporal laterally; medial portion with process corresponding to region of contact with columella auris; ventral portion contacts glenoid cavity of retroarticular process of mandible; ventromedial portion contacts rear end of pterygoid; quadrate tapers dorsoventrally. DENTARIES: anterior end curved towards opposite hemimandible; lateral face convex with mentonian foramen medially located; after this foramen, dentary branches into dorsal (longer) and ventral processes; dorsal surface with 32–36 conical rear facing teeth. SPLENIALS: tapered anteriorly, in the region of contact with dentary; anterior mylohyoid foramen limited by angular. ANGULARS: elongated, triangular, tapered posteriorly, contacting dentary anterodorsally and splenial anteroventrally; posterior mylohyoid foramen near suture with splenial; angular˗splenial joint visible in ventral view. COMPOUND BONE: correspond approximately to three-quarters of mandible; surangular crest with rounded dorsal edge and lower than prearticular crest; in lateral view, compound bone tapers anteriorly, fitting between dorsal and ventral processes of dentary; posterior foramen of surangular exposed.

Distribution and natural history ( Fig. 6 ). Chironius flavolineatus is distributed in the Chaco of department of Santa Cruz, Bolivia; department of Amambay, Paraguay, and the Cerrado, Caatinga, Amazonian, and Atlantic Forest biomes in Brazil throughout the states of Amazonas, Amapá, Maranhão, Pará, Tocantins, Ceará, Rio Grande do Norte, Paraíba, Pernambuco, Alagoas, Sergipe, Bahia, Goiás, Mato Grosso, Mato Grosso do Sul, Minas Gerais, and São Paulo from 3–1171 m above sea level, hereafter asl (generally 100–400 m asl). We examined photographs of a supposed specimen of C. flavolineatus from Peru (UNMSM 2889) ( Lehr 2002) and concluded this specimen is not a C. flavolineatus as it has no vertebral stripe and other diagnostic characters of this taxon. Thereby, as far as we know there are no records of C. flavolineatus to Peru.

Some preserved specimens of C. flavolineatus (MNRJ 3981, 17183, 17155) had amphibians ( Scinax gr. fuscovarius, Scinax gr. x-signatus, a non-identified species of Hylidae , and Leptodactylus fuscus ) as stomach contents ingested in posterior-anterior direction. Three specimens of C. flavolineatus were observed on April 28, 2006 by one of us (BH) entwined on the litter of an anthropized fragment of Atlantic Forest in the municipality of Salvador, state of Bahia, Brazil. During the present report no aggressive behavior or male combat was observed. After approximation, snakes split up and tried to escape. One specimen (a female, total length 1002 mm, Figs. 2 A– B) climbed a tree and was captured. At this moment specimen held a cloacal discharge, opened its mouth, and attempted to bite. This specimen was held in captivity and after eight days laid four eggs. Three months later, on August 10, two hatchlings were born ( Figs. 2 G–H). Some specimens examined in the present study (MZUSP 14172; CHUNB 21959, 24908) showed 3– 8 eggs in the oviduct.

Figures

FIGURE 1. Color pattern variation in preservative of adults of C. flavolineatus from Bolivia (A – B, MNKR 2254), Paraguay (C – D, MNHNP 5201), and Brazil (E – H, UFPB 4669). Photos by R. Sosa (A – B) and M. Motte (C – D).

FIGURE 2. General view of adult (A – F) and hatchlings (G – H) of Chironius flavolineatus in life. Photos by D. Santana (C), W. Pessoa (D), and C. Cintra (E – F).

FIGURE 3. Asulcate (A, D), sulcate (B, E), and lateral (C, F) views of the hemipenis of C. flavolineatus (upper, UFS 419) and C. brazili (lower, MZUFV 1746). Arrow indicates region of medial constriction of hemipenis slightly covered with spinules.

FIGURE 4. Lateral (A – C) and ventral (D) views of cephalic glands of C. flavolineatus (B, UFS 1329) and C. brazili (A, C, D, MCNR 2077). D. g. = Duvernoy gland; H. g. = Harder gland; i. g. = Infralabial glands; ls. g. = Lateral sublingual glands; ms. g. = Medial sublingual gland; n. g. = Nasal gland; p. g. = Premaxilar gland; and s. g. = Supralabial glands.

FIGURE 5. Dorsal (A), ventral (B), posterior (C), and lateral views (D) of the skull of Chironius flavolineatus (UFS 1329).

FIGURE 6. Geographic distribution of Chironius flavolineatus, C. brazili, and C. diamantina.