Allobates ignotus, Anganoy-Criollo, Marvin, 2012

Anganoy-Criollo, Marvin, 2012, A new species of Allobates (Anura, Dendrobatidae) from the western flank of the Serranía de Perijá, Colombia, Zootaxa 3308, pp. 49-62 : 50-60

Allobates ignotus sp. nov.

Spanish name. Rana nodriza de la Serranía de Perijá English name. Nurse frog of the Serranía de Perijá

Holotype. ICN 55434 (field number PR 17142) an adult female with ova, from finca Buena Vista, Zumbador river, 580 m, vereda Nueva Granada, Municipio La Jagua de Ibirico, Departamento Cesar, Colombia. Collected by O. V. Castaño, G. Cárdenas, P. Galvis on March 16, 1996.

Paratypes. ICN 55435–55436 data as holotype. ICN 55427–55433 from quebrada El Indio, 520 m, corregimiento La Victoria de San Isidro, Municipio La Jagua de Ibirico, Departamento Cesar, Colombia, collected by P. Ruiz-Carranza, M. Cristina-Ardila, V. Rueda, J. Sánchez on March 19, 1996. ICN 55437–55439 from quebrada El Veranero, 400 m, vereda El 11, Municipio El Becerril, Departamento Cesar, Colombia; collected by L. M. Escobar on June 10, 2011.

Definition and diagnosis. A small Allobates characterized by 1) SVL adult males 16.4–18.3 (17.4±0.9, n = 3), adult females 16.9–20.9 (19.4±1.5, n = 7); 2) disc on Finger III slightly expanded, 1.1–1.5 times the width of the adjacent phalange; 3) when adpressed, Finger I is equal to or longer than Finger II, Finger I 0.9–1.2 times longer than Finger II; 4) weakly differentiated lateral keels on all fingers; 5) disc on Toe IV weakly expanded, the disc 1.1–1.8 times the width of the adjacent phalange; 6) fringes on all toes (pre and post-axial side), slightly expanded, and those on pre-axial sides of the toe II, III and IV, more evident; 7) weakly differentiated outer metatarsal fold present, low, distally in tubercle-like form; 8) basal toe webbing between II–IV, II (2-–2) – (31/4–31/2) III (23/4–3) – (4–4+) IV; 9) pale dorsolateral stripe present, extended from eyes to the level of middle of insertion of thigh and does not drop onto thigh; 10) diffuse pale oblique lateral stripe as a series of spots, not forming a stripe, extending from groin to more than middle body; 11) ventrolateral stripe present; 12) gular-chest region cream, sexually dimorphic; in adult males uniformly dark, brown to grayish brown, and in adult females cream with scarce brown stippling, but not dark; 13) abdomen cream, in adult males anterior darker with brown to grayish brown stippling and adult females with slight brown stippling; 14) Finger III swollen on preaxial surface in adult males; 15) black arm band absent; 16) median lingual process absent; 17) cloacal tubercles absent; 18) testes cream, without melanophores; 19) pattern of coloration on dorsum brown to dark brown, in adult females with one wide band from snout to urostyle, delimited by the pale dorsolateral stripe and adult males with interorbital band and two larger square spots, one on scapula and other on middle dorsum.

Allobates ignotus is a small trans -Andean nurse frog than resembles other small cis -Andean species in the genus Allobates . Allobates ignotus differs among the species of Allobates by having dorsolateral stripes (no dorsolateral stripes in algorei , brunneus , chalcopis , goianus , granti , humilis , nidicola , picachos , subfolionidificans , undulatus , zaparo ), a continuous and defined ventrolateral stripe (no ventrolateral stripe in bromelicola , caribe , chalcopis , crombiei , humilis , marchesianus , nidicola , picachos , sanmartini , subfolionidificans , undulatus ; as an interrupted line in algorei , caeruleodactylus , gasconi ), diffuse pale oblique lateral stripe (no diffuse pale oblique lateral stripe in bromelicola , caribe , chalcopis , conspicuus , crombiei , fratisenescus , fuscellus , hodli, insperatus , masniger , myersi , sumtuosus , talamancae , undulatus , vanzolinius ) as a short series of spots (diffuse pale oblique lateral stripe dividing dark lateral band in algorei , brunneus , gasconi , goianus , humilis , juanii , paleovarzensis , ornatus , pittieri ; as a short pale solid line in femoralis and kingsburyi ; or as a complete line from eye to groin in olfersioides , picachos , ranoides ), adult males with swollen preaxial side of the Finger III (not swollen in algorei , brunneus , caeruleodactylus , chalcopis , conspicuus , fratisenescus , granti , hodli, humilis , insperatus , juanii , kingsburyi , marchesianus , masniger , nidicola , olfersioides , pittieri , spumaponens , subfolionidificans , talamancae , undulatus , vanzolinius ), basal toe webbing between toes II–III–IV (moderately extended between toes I–IV in alessandroi and toes I–V in mandelorum ; basal only between toes III–IV in cepedai , chalcopis , fratisenescus , fuscellus , gasconi , masniger , olfersioides , ornatus , paleovarzensis , subfolionidificans , sumtuosus , undulatus ; and basal between I–IV in sanmartini ) and by dorsum smooth or slightly granular on posterior dorsum (which differs from species of Allobates femoralis group, femoralis , hodli and zaparo by having dorsum strongly granular) (Table 1), except for A. mcdiarmidi , A. melanolaemus , A. spumaponens and A. trilineatus and the trans -Andean A. niputidea and A. wayuu .

Allobates ignotus is morphologically very similar to the trans -Andean A. wayuu and also resembles A. mcdiarmidi , A. melanolaemus , A. niputidea , A. spumaponens and A. trilineatus . Allobates ignotus differs from A. wayuu (state of characters in parenthesis) by having ventral pattern uniformly cream and adult males with uniformly dark brown on gular-chest region (dark brown mottled in both sexes and no dark brown gular-chest region), diffuse pale oblique lateral stripe as a series of spots (as short stripe, not in series of spots), dorsolateral stripes joined at level of the middle of insertion thigh and not reaching thigh (extend to top of thigh and joined with paracloacal marks) ( Fig. 1–2 ), and by adults of A. ignotus being larger than adults of A. wayuu (16.4–18.3 mm, x = 17.4± 0.9 in males and 16.9–20.9 mm, x =19.4± 1.5 in females of A. ignotus and 13.6–16.1 mm, x = 16.1± 0.8 in males and 15.8–19.7 mm, x = 17.5± 0.9 in females of A. wayuu ); from A. niputidea by having gular-chest region uniformly dark brown in adult males (black solid), slightly keels on Finger III (absent), and by larger size than A. niputidea (adult males reach 17 mm and adult females reach 18 mm of SVL); from A. spumaponens by uniformly dark brown gular-chest region in adult males (dark spotting on chin and laterally), by Finger III swollen on preaxial surface in adult males (not swollen) and by having keels and fringes on fingers and toes, respectively (without fingers and keel); from A. mcdiarmidi by having dark brown gular-chest region in adult males (discrete and scarce stippling; see Grant and Rodríguez, 2001: Fig. 15), by lack of pale discrete spots on posterior dorsum (pale discrete spots) and by adults of smaller size than A. mcdiarmidi (22.5–24.3 mm in males and 26 mm in females); from A. melanolaemus by dark brown gular-chest region in adult males (solid black), slightly defined dorsolateral stripe (more conspicuous) and adults of lesser size (21.1–23.4 mm in adult males and 21.3–23.6 mm in adult females); and from A. trilineatus by moderated conspicuous swollen Finger III (strongly swollen), anterior abdomen darkened by brown to grayish stippled that fades posteriorly in adult males (abdomen weakly to conspicuously mottled [ventral coloration only of specimens from the type locality, see Grant and Rodríguez 2001: Fig. 3 ; see comments in Grant et al. 2006: Pag. 131]) and adults slightly larger (15–17.7 mm in adult males and 15.2–19.3 mm in adult females).

The cis -Andean Allobates species that has the northernmost distribution is A. algorei , a species described from the eastern flank of the Cordillera Oriental from San Cristóbal, Venezuela, between the Cordillera Oriental of Colombia and Cordillera of Mérida of Venezuela ( Barrio-Amorós and Santos, 2009). Allobates ignotus differs from A. algorei by having basal toe webbing (absent), Finger III swollen on preaxial surface in adult males (not swollen), continuous and lineal ventrolateral stripe (wavy and interrupted) and by keels on fingers (absent). Two other species, Allobates juanii and A. cepedai , also occur on the foothills of the eastern flank of the Cordillera Oriental, Meta, Colombia. Allobates ignotus differs from A. juanii by having swollen Finger III (not swollen), diffuse pale oblique lateral stripe as a series of spots (as a short stripe, interrupting black lateral band, i.e., directed obliquely from groin to dorsum), dark gular-chest region in adult males (uniformly cream), dorsal pattern of adult females as one wide dark brown band (adult males and adult females with hourglass pattern) and by smaller size (SVL 19–20.5 mm in adult males and 19.8–22.5 mm in adults females of A. juanii ); and from A. cepedai by having ventrolateral flanks smooth (granular), diffuse pale oblique lateral stripe as a series of spots (short stripe) and by uniformly dark gular-chest region in adult males (gray with dark marbled [free translation from the original description of Morales, 2002 “2000”]).

The distributions of Colostethus ruthveni (Sierra Nevada de Santa Marta, Colombia), Aromobates saltuensis (highland between the Cordillera Oriental, Colombia, and the Cordillera de Merida, Venezuela) and Aromobates tokuko (eastern flank of the Serranía of Perijá) are geographically close to the Serranía de Perijá and various authors have proposed biogeographic links between these upland areas ( Duellman 1979, Hernández et al. 1992, Lynch 1996, Lynch 2008). Allobates ignotus differs easily from C. ruthveni by having ventrolateral and oblique lateral stripes (absent), discs on fingers slightly expanded (expanded), ventral skin smooth (granular, low granules), and by lesser size (adult males of C. ruthveni reach 20 mm and adult females reach 24 mm of SVL); from A. saltuensis by having basal toe webbing between toes II–III–IV (basal in all toes), ventrolateral stripe present (absent), disc on fingers slightly expanded (expanded), tarsal keel weak and low and distally as tubercle-like (as fold and not tubercle-like), swollen Finger III (not swollen), uniformly dark gular-chest region in adult males (grayish brown with dark brown mottled), and by smaller size (adults 22–27 mm of SVL); and from A. tokuko by ventrolateral stripe present (absent), having basal toe webbing between toes II–III–IV (basal between toe I–IV), skin of the flanks smooth (moderately granular) and swollen Finger III (not swollen).

Measurements of the holotype (in mm). Snout-vent length, 19; forearm length, 4.14; hand length, 4.76; shank length, 9.12; foot length, 8.34; head width, 6.66; head length, 7.56; eye length, 2.84; eye to nostril distance, 1.64; distance between centers of the nostril, 2.52; snout length, 3.64; interorbital distance, 2.12; greatest diameter of tympanum, 1.14.

Description of the type series. Adult males ( Fig. 2 B) 16.4–18.3 SVL (17.4±0.9, n = 3), with testes unpigmented (cream) and vocal slits. Adult females ( Fig. 2 A) 16.9–20.9 SVL (19.4±1.5, n = 7), mature ova animal pole dark brown and cream ventrally. Adult females slightly larger than adult males.

Body slender. Head width slightly less wide than body (at scapular girdle); head length 36.6–41.4% SVL and head width 33–38.2% SVL, head longer than wide, 1–1.2 times head width. Snout weakly rounded to bluntly rounded in dorsal view and weakly rounded in profile, snout sloping projecting beyond upper lip. Canthus rostralis straight and gently rounded. Loreal region flat, vertical and not sloping outward to lip. Eye length 35–41% of head length. Eye-nostril distance 49.7–70.1% of eye length and 43.6–58.9% of snout length. Nares slightly projecting and directed laterally, visible from the front, from below and barely from above, with a low, weakly rim and a raised fleshy area posterodorsally on the edge of the nostril in magnification. Anterolateral half of tympanum well defined, rest of tympanum concealed posterodorsally by low supratympanic bulge. Length of the visible tympanum 32.7–54% eye length. Short teeth on maxillary arch. Tongue elliptical, anterior one third attached and posterior free, without median lingual process.

Forelimbs moderate, forearm 20–26.4% SVL. Hand length 23.5–28.7% of SVL and 1–1.2 times of forearm length ( Fig. 3 B). Finger discs weakly expanded; disc on Finger III is 1.1–1.5 wider that adjacent phalange. Finger III of two (55429, 55436) adult males swollen along preaxial side, postaxial side not swollen. Pre- and postaxial sides of the fingers with weakly keels, barely differentiated from finger. Metacarpal fold as an ovoid cream spot (commonly), as weak fold (holotype) to a low and small tubercle (rarely), not continuous with keel of the postaxial side of the Finger IV. Finger I equal to (including the holotype) or slightly longer than Finger II (when appressed), or Finger I (3.5–4.5 mm) equal to longer than Finger II (3.4–3.8 mm). Finger II extends to midlevel of distal subarticular tubercle of Finger III; Finger IV reaches distal subarticular tubercle of Finger III. Relative length of fingers (when appressed to finger III) IV<II=I<III. Subarticular tubercles usually 1-1-2-2 or rarely 1-1-2-1. All tubercles protuberant, except distal subarticular tubercle of Finger IV weakly and poorly defined (including the holotype); subarticular tubercles rounded or elongated, thenar tubercle elliptical, palmar tubercle subcircular; thenar tubercle from one third to the half (including the holotype) than palmar.

Hindlimbs moderate, shank 43–51.6% SVL and foot 38.6–48.7% SVL. Toes disc moderately expanded. Disc on Toe IV slightly wider than disc on Finger III. Relative length of appressed toes I<II<V<III<IV. Disc of Toe III extends beyond penultimate subarticular tubercle of Toe IV; Toe V reaching penultimate subarticular tubercle of Toe IV. Feet ( Fig. 3 C) with basal toe webbing between toes II–III–IV, absent between I–II and IV–V; toe webbing formula II (2-–2) – (31/4–31/2) III (23/4–3) – (4–4+) IV. Fringes on all toes, weakly expanded but more evident on preaxial sides of toe II, III and IV. Outer metatarsal fold weak, continuous with postaxial fringe of Toe V, not reaching outer metatarsal tubercle, sometimes tubercle-like, but not in the holotype. Tarsal keel weak, low and straight, distally tubercle-like, not continuous with fringe of preaxial side of toe I but in contact with inner metatarsal tubercle, diagonal from inner metatarsal tubercle to half of the tarsal length. Subarticular tubercles strongly protuberant, rounded to elongated. Subarticular tubercles 1-1-2-3-2. Inner metatarsal tubercle elongate. Outer metatarsal tubercle round, diameter more than half of length of inner metatarsal tubercle. Median metatarsal tubercle as a weak raised area, ill defined.

Dorsal surfaces smooth, in adults with granules above sacrum and on tops of thighs. Ventral and lateral surfaces smooth. Postrictal and paracloacal tubercles not detected. Preaxillary surface with aspect of bulging glandular tissue (= postrictal bulge). Tubercle on eyelid absent in preservative (Ethanol 70%), but low and conspicuous in life (ICN 55437) ( Fig. 4 ). A small cloacal sheath covering cloaca (see discussion in Grant et al. 2006).

Coloration in life. Coloration based on field notes of Pedro Ruiz-Carranza, March 16, 1996 (PR 16872–73, PR 17142–44) and Lina María Escobar , June 10, 2011 (LEP 207; Fig. 4 A, B) as follow. Four adult females (ICN 55427–55428, ICN 55434–55435) and one juvenile female (ICN 55437) with dorsum light brown with dark brown hourglass pattern. Dorsolateral stripe light brown. Interorbital band dark brown. Lateral surfaces covered by a dark brown to black band, extended from snout to groin. White small spots from groin to middle body. Ventrolateral line cream to white, extending from groin to lip. Dorsal surface of forelimbs and hindlimbs dull yellow with dark brown bands and ventral surface pinkish. Gular and abdominal region iridescent cream. Paracloacal marks golden yellow. Iris reddish orange with black dots.

One adult male (ICN 55436) has the dorsal surface of head and body olive-brown and a large irregular blackish spot on vertebral region. Broad blackish band on flanks. Ventrolateral flanks with a white ventrolateral stripe. Upper lip pearly white. Gular-chest region and lateral region of the belly blackened with white spots on axilar surface. Hind-limbs brown with black bands. Ventrolateral region on hind-limb near to groin and paracloacal marks bright yellow. Forelimbs cream.

Coloration in preservative. Dorsum pale brown or brown with dark brown blotches; in adult females the blotches forming continuous broad band extending from snout to the distal end of the urostyle and in adult males the blotches are arranged in one interorbital band, one scapular and large, square dorsal spots, and small spots above sacrum, forming hourglass pattern. In juveniles the large square spots forming hourglass pattern. Granules dark brown. Pale dorsolateral stripe inconspicuous cream to cream, extending from posterior edge of eyelid to the distal end of urostyle, not extending onto top of thighs; when inconspicuous, have abundant dark brown stippling. Eyelid grayish dark brown. Flanks with a dark brown band, extending from groin to tip of snout. A group of small pale cream irregular spots on groin, extending to middle of body or to posterior of arm insertion; pale spots not forming band ( Fig. 3 A). Ventrolateral stripe white in adults and cream in juveniles (i.e., inconspicuous), straight, extending from the groin to above arm insertion or to below tympanum; rarely continuous with white stripe on upper lip. Region on upper lips cream with scarce to abundant brown stippling. Ventrolateral flanks white to cream, uniformly stippled brown or white mottled. Tympanum dark brown above and cream below with scarce or abundant brown stippling. Supratympanic fold dark brown or black. Ring on nostril brown to dark brown. Axilla white to transparent and preaxilla (i.e., antero-dorsally arm insertion) whitish. Concealed surface of the groin white.

Gular-chest region cream, belly white or yellowish cream. In adults, coloration on gular-chest region sexually dimorphic; adult males brown to grayish brown fading uniformly on anterior belly or covering entire abdomen; in adult females and juveniles cream with scarce or abundant brown stippling.

Dorsal surfaces of thighs cream to dark brown and shanks commonly dark brown to rarely light brown with inconspicuous to well defined dark brown stripes; these stripes end in a spot on the anterior surface of the thigh and sometimes forming a longitudinal stripe. Anterior surfaces of thighs cream, antero-ventral region, near groin white; posterior surfaces of thighs spotted dark brown. Paracloacal marks cream or white, extending longitudinally to middle or beyond of thigh. Concealed region of shanks white. Ventral surfaces of hindlimbs (thigh and shank) white to pale cream. Foot cream above with dark brown mottled or banded and below dark brown. Top of discs grayish dark brown.

Dorsal surfaces of the arm white to cream and forearm cream with scarce or abundant brown stippling. Diffuse dark brown bands on forearm. Anterior surfaces of arm with diffuse longitudinal brown stripe; posterior surface of arm with diffuse brown spots. Ventral surface of arm cream and of forearm dark brown with two or more small circular cream spots, disposed longitudinally from hands to elbow. Hands cream above with scarce or abundant brown stippling and palmar surface dark brown. Top of discs dark brown to pale dark brown.

Distribution and ecology. Allobates ignotus inhabits the western flank of Serranía de Perijá, Colombia, from 400 to 900 meters of altitude ( Fig. 5 ). The habitat lies within humid forest, ranging from 24°–28° centigrade with 2000 to 4000 mm of annual precipitation. Individuals were found active by day at the edge of a stream or in the leaf-litter near to the stream. In the quebrada El Veranero, the adult males were heard calling from leaf-litter in June, 2011, and also free-swimming tadpoles were observed in the edge of the stream.

The forest near the quebrada El Veranero, where three juvenile females were collected (ICN 55437–39) has been fragmented and degraded by illegal crops, marihuana ( Cannabis sativa ) and Amapola ( Papaver rhoeas ), sprayed with herbicide and pesticides and heavily grazed by livestock. The habitat in this place is an intervened forest (field notes of L. M. Escobar, June 10, 2011). Dendrobatid frogs are susceptible to habitat degradation, inasmuch as embryos and tadpoles depend of the water and adults occur in places where illicit crops are exposed to herbicide gliphosate ( Lynch and Arroyo, 2009). The ability of tolerating the environmental changes by A. ignotus is unknown. More data is required to assess the current threats of A. ignotus to be evaluated for the IUCN red list.

Etymology. The specific epithet is a noun in apposition and the word is an adjective in Latin, ignotus = unknown, in reference to the incomplete knowledge of species of Allobates in Colombia and likewise the species that were included formerly in Colostethus sensu lato, now in Colostethus , Hyloxalus and Rheobates of this country.

Figures

FIGURE 1. Adult female (A. ICN 43229) and adult male (B. ICN 43234) in dorsal (up) and ventral (down) view of Allobates wayuu. The dorsolateral stripe drop on thigh and join with the paracloacals marks (white arrows).

FIGURE 2. Adult female (A) and adult male (B) in dorsal (up) and ventral (down) view of Allobates ignotus new species. A. ICN 55434 holotype and B. ICN 55436 paratype.

FIGURE 3. Flank (A) and foot (C) of the adult female, holotype ICN 55434, and hand with swollen Finger III (B) of the adult male, paratype ICN 55436, of Allobates ignotus new species. Scale bars, equal 1 mm.

FIGURE 4. Allobates ignotus new species in life. Lateral (A) and dorsal (B) view of a juvenile female (ICN 55437). Photo by L. M. Escobar.

FIGURE 5. Distribution of the trans - Andean Allobates in Colombia, Allobates ignotus new species (stars), Allobates niputidea (triangles), Allobates talamancae (squares) and Allobates wayuu (circle). White star indicates the type locality of Allobates ignotus. Records based on specimens deposited in the Laboratorio de Anfibios, Instituto de Ciencias Naturales, Universidad Nacional Colombia (ICN).