Hyloxalus italoi, Páez-Vacas & Coloma & Santos, 2010

Páez-Vacas, Mónica I., Coloma, Luis A. & Santos, Juan C., 2010, Systematics of the Hyloxalus bocagei complex (Anura: Dendrobatidae), description of two new cryptic species, and recognition of H. maculosus 2711, Zootaxa 2711, pp. 1-75 : 31-39

Hyloxalus italoi new species

Hylixalus bocagii (non Jiménez de la Espada)— Boulenger 1882:138.

Hyloxalus bocagei — Grant et al. 2006:136, 168.

Holotype. QCAZ 33197 ( Fig. 13, virtual animation), adult male from Ecuador: Provincia Pastaza: Reserva de Bosque Tropical Fundación Hola Vida (01° 37' S, 77° 54' W; 831 m above sea level), obtained on 30 March 2007 by Diego Almeida-Reinoso, Ítalo G. Tapia and Mónica I. Páez.

Paratopotypes. QCAZ 33191–33213 , same data as holotype ; QCAZ 25650 , 25702–25708 , obtained on 28–29 June 2003 by Ítalo G. Tapia and Kathryn Elmer ; QCAZ 37168 , 37171–37174 , 37195–37196 , 37202– 37205 , 37207–37210 , 37213–37214 , obtained on 9 July 2007 by Luis A. Coloma, Ítalo G. Tapia, Carolina Proaño-Bolaños, Paula Peña-Loyola and Mónica I. Páez .

Referred specimens. QCAZ 3344 Miazal (2° 37' 23.0514"S, 77° 47' 41.6394"W), 423 m , Provincia Morona Santiago, Ecuador, obtained on 24 July 1992 by Paulina Mendoza, USNM 281997–99, Miazal, obtained on February 1956 by Manuel Olalla ; QCAZ 6237–38 , Santiago , Provincia Morona Santiago, obtained 12 July 1994 by Martin Schiller ; QCAZ 24328 , Santiago , obtained on 28 December 2000 by Samael Padilla and Juan Carlos Santos ; QCAZ 27411 , 27445–46 , Santiago , obtained on 24 April 2004 by David C. Cannatella, Luis A. Coloma, Juan Carlos Santos and Ítalo G. Tapia , QCAZ 29185 , 2 – 2.3 km W Santiago , 296 m , obtained on 24 April 2004 by David C. Cannatella, Luis A. Coloma, Juan Carlos Santos and Ítalo G. Tapia; QCAZ 27182–88 , 27190–91 , 28804 , Santiago , Río Santiago, 310 m , obtained on 30–31 March 2004 by Catherine Darst and Diego A. Paucar; USNM 281961 , 281986–95 , N of Arapicos , Llushin, obtained on January 1955 by Ramón Olalla ; USNM 281996 , Macuma , obtained on October 1953 by B. Pazmiño ; USNM 317039–64 , 560215–29 , vicinity of Shaim , on the Alto Comaina, tributary of Cenepa, Amazonas, Peru ; USNM 317065–66 , Chigkishinuk entse, on the Río Huampami, tributary of Río Cenepa ; USNM 317067–68 , headwaters of Río Kagka , tributary of Río Cenepa ; USNM 317069–73 , 317075 , vicinity of Huampami on the Río Cenepa, 210 m ; USNM 317074 , Huampami , Quebrada Tsunup, on the Río Cenepa, 210 m ; USNM 317076 , 0.5 m N of Huampami, on the Río Cenepa , 210 m ; USNM 317077–103 , 317608 , 560200–08 , Huampami , Quebrada Sasa, on the Río Cenepa, 210 m ; USNM 317109 , S of Huampami, Apinkam entse, on the Río Cenepa , 210 m ; USNM 317104–08 , 560209–10 , USNM 317122 , Aintami entse, on the Río Cenepa ; USNM 317117–21 , 560213–14 , vicinity of Aintami, on the Río Cenepa ; USNM 317110–16 , 317142 , vicinity of Río Kayamas , tributary of Río Cenepa ; USNM 317123–26 , across the Río Cenepa from Chigkan entse ; USNM 317127–36 , vicinity of San Antonio , on the Río Cenepa ; USNM 317137–41 , 560211–12 , vicinity of Sua , on the Río Cenepa, obtained between 13 July and 30 August 1977 by Roy McDiarmid ; RWM 14237–38 , 14335–36 , 14486–87 , 15690 , Galileo ; RWM 13939–40 , Chiringa ; RWM 14392–96 , La Poza ; RWM 14403, Shaime , obtained on 29–31 January 1977 by Roy McDiarmid .

Diagnosis. A species of the genus Hyloxalus as defined by Grant et al. (2006), based on the following features: (1) dorsal coloration cryptic, brown or black; (2) pale oblique lateral stripe present (although reduced); (3) pale dorsolateral stripe absent; (4) pale ventrolateral stripe absent; (5) dorsal skin texture posteriorly granular; (6) toe webbing extensive; (7) third finger of adults not swollen; (8) finger disc moderately expanded; (9) median lingual process absent; (10) larval vent tube dextral; (11) larval oral disc not umbelliform; (12) larval oral discs emarginated; (13) tested unpigmented; (14) dark throat collar absent.

A species with (1) mean SVL in adult males 23.6 mm (19.1–27, SD = 1.4, n = 94) and in adult females 25.8 mm (21.6–30.1, SD = 1.6, n = 111); (2) disc of Finger IV expanded less than 1.5 times the width of adjacent phalange; (3) Finger II shorter, equal or longer than Finger III; (4) fringes present on fingers; (5) disc of Toe IV expanded less than 1.5 times the width of adjacent phalange; (6) fringes present on toes; (7) outer metatarsal fold present; (8) extensive toe webbing, formula I 1—(1½–2½) II (1–1½)—(2–3 -) III (1–2 -)—(2½– 3½) IV (3–3½)—(1–2 -) V; (9) oblique lateral stripe reduced, a small bar or a series of 3–5 dots at groin level; (10) dorsum with three large blotches; (11) gular-chest region brown with white marks in adult males, creamcolored or with very subtle brown spots in adult females; (12) venter white with brown marks in adult males, cream in adult females; (13) sexual dimorphism in ventral coloration present; (14) tadpoles brown with large and blurry darker blotches on tail, a belt-like mark on body-tail junction and, in vivo, two pale marks on each side of oral disc and two on each side of body at spiracle level; (15) tadpole spiracular opening oriented dorsoposteriorly; (16) call is a long trill composed of single pulsed notes.

Hyloxalus italoi is similar to those species that exhibit extensive toe webbing and lack oblique lateral stripe or it is reduced at groin level ( H. abditaurantius Silverstone , H. betancuri Rivero and Serna , H. chocoensis Boulenger , H. edwardsi Lynch , H. faciopunctulatus Rivero , H. leucophaeus Duellman , H. maculosus , H. ruizi Lynch , H. yasuni ). It is distinguished from these species by the following characters: H. abditaurantius has an orange spot on the calf, absent in H. italoi . Hyloxalus betancuri lacks a postmandibular tubercle; ventral coloration in females (holotype CJS 2372, an adult female and the only specimen known of the species) is dark brown with small white dots, whereas females of H. italoi are ventrally cream-colored. Hyloxalus chocoensis has a squared dorsal mark and testes enlarged. Hyloxalus edwarsi and H. ruizi are distinguished from all species within the genus by having a cloacal funnel. Hyloxalus faciopunctulatus lacks a V- shaped dorsal blotch at scapular level. Hyloxalus leucophaeus lacks outer metatarsal fold and sexual dimorphism in ventral coloration. Hyloxalus maculosus differs in gular-chest region of adult males; they do not exhibit white spots over a dark brown background ( Fig. 3). Adult specimens of H. yasuni are very similar to H. italoi , nevertheless, this two species differ in genetic sequences, tadpole morphology, and call parameters (see H. italoi Comments ).

Description of holotype. ( Fig. 13, virtual animation). Male, SVL 24.5 mm; head slightly longer than wide; head length 39.4% of SVL; head width 38.9% of SVL; snout subacuminate in dorsal view, angular in lateral view; loreal region slightly concave; nostrils slightly protuberant laterally; eye-nostril distance 67.2% of eye length; supratympanic bulge diffuse, covering upper edge of tympanum; tympanum diameter 36.8% of eye length.

Arm length 21.7% of SVL; Finger II shorter than Finger III; fingers unwebbed; fringes present; terminal discs expanded less than 1.5 times diameter of adjacent phalange; subarticular tubercles round, small, those of Fingers II and III slightly oval; outer metacarpal tubercle large, round and protuberant; inner metacarpal tubercle at base of the thumb, small, elliptical and protuberant, approximately one third of outer metacarpal tubercle; unpigmented outer edge of metacarpus from Finger V to outer metacarpal tubercle. Tibia length 46.9% of SVL; foot length 44.3% of SVL; outer metatarsal fold present; inner sigmoid tarsal fold present on distal half of tarsus; outer metatarsal tubercle round; inner metatarsal tubercle larger than outer, elliptical; subtle unpigmented protuberance between the two metatarsal tubercles; toes more than a half webbed, webbing formula I 1—2 - II 1—2 III 1—3 - IV 3 + —1 V; lateral fringes extensive; terminal discs expanded less than 1.5 times diameter of adjacent phalange; subarticular tubercles small, round; supernumerary tubercles absent.

Skin on dorsum, limbs, flanks and venter smooth; a few tubercles on right flank; round tubercle posterior to mouth; anal sheath conspicuous. Tongue twice as long as wide, thinner and broader posteriorly, posterior half not attached to mouth’s floor. Testis white.

Color in preservative (~70% ethanol). Dorsum of head and body dark brown, slightly olive tan; three darker brown blotches on dorsum, an interorbital mark, a V-shaped mark at scapular level and a bar at sacral level; flanks dark brown with white spots towards the venter; dark brown stripe present from posterior corner of eye to the arm-body junction. Cream-colored spots present at the posterior corner of the eye; loreal region dark brown with scattered diffuse bronze spots. Oblique lateral stripe reduced to 3–5 cream dots, anterior to the groin. Forelimbs dark brown, transverse bars not visible, a cream spot in the dorsal surface of arm near arm-body junction; dorsal surfaces of hind limbs dark brown, transverse bars conspicuous, a dark blotch at back of the knee; ventral surfaces cream-colored with brown spots. Gular-chest region dark brown with large white spots; venter cream flecked with brown; axillas translucent with two small brown bands. Palmar and plantar surfaces dark brown; webbing translucent.

Color in life. ( Fig. 3D). Iris coppery brown with copper flecks; dorsum brown; dorsal blotches dark brown; a reddish brown band posterior to each eye; canthus rostralis brown with small white spots, flanks same color as dorsum; tympanum cream-colored; supratympanic bulge brown covering upper edge of tympanum. Pale oblique lateral stripe reduced to a series of 3–5 pale dots anterior to the groin. Dorsal surfaces of limbs reddish brown; a reddish brown spot in dorsal surface of arm, near arm-body junction; internal surfaces of thighs yellow flecked with brown; groin yellowish brown. Gular-chest region dark brown with small white dots, venter iridescent white flecked with dark brown; limbs ventrally cream-colored with brown traces, the tibia acquires a blue shade with small brown spots; palmar and plantar surfaces brown, the edges yellowish; yellowish cream spot on edge of palms, between the two metacarpal tubercles; webbing yellowish cream (MIP field notes, 31 March 2007).

Variation. Variation in measurements is given in Tables 7 and 8. Variation in color patterns is depicted on Figs. 5E – 7E. Specimens from type locality are reddish brown (n = 79: 36 males, 43 females). Gular-chest region in males is dark brown with white spots, this coloration can be either collar-shaped or extended posteriorly to mid venter; throat in females cream flecked with brown, this coloration can extend posteriorly to mid venter. Bronze or cream dots present on loreal region. Finger II shorter than III, the difference in lengths can be very subtle. Toe webbing formula I 1—(1½–2½) II (1–1½)—(2–3 -) III (1–2 -)—(2½–3½) IV (3– 3½)—(1–2 -) V .

Referred specimens from Santiago (n = 25: 10 males, 15 females) show slight differences in ventral coloration. Gular-chest region color is due to a variable concentration of brown stippling, large white spots absent, cream-colored in females, a very subtle stippling sometimes present; white dots on loreal region absent; Finger II shorter than III.

Referred specimens from Río Cenepa (n = 102; 47 males, 55 females) have subacuminate snout. Finger II slightly shorter than Finger III. In males, gular-chest region with lateral bands of different lengths, from very small spots at each side of throat (e.g. USNM 317059 , 317064 ) to long spots at each side that join together and form a collar-like band (e.g. USNM 317039 , 317047 , 317062 ) (see Coloma, 1995:10), and gular-chest region completely brown occasionally (e.g. USNM 317049 , 317053 , 317054 ). In females, gular-chest region creamcolored, sometimes subtly stippled, sometimes brown dotted anterior to arm-body junction, or even with a transverse band on the chest and a spot on the chin .

Three recently metamorphosed individuals (QCAZ 7487a, 7487b, 33209–33210) have SVL of 11.1–12.9 mm (mean = 11.9).

Variation of coloration in life: QCAZ 33191 (adult female, Fig. 4D). Body lightly lighter than holotype, but more reddish. Dorsal yellow spot on arm at arm-body junction. Venter white; gular-chest region white slightly flecked with brown; limbs translucent ( MIP field notes, 31 March 2007) .

Tadpole. ( Figs. 11, 14). The following description is based on a specimen in Stage 25 ( QCAZ 33220 a, Figs. 14A–C), obtained along with the species holotype ( QCAZ 33197 ) at Reserva Hola Vida. All measurements provided are in millimeters. Total length 21.2; body ovoid, ventrally depressed; body length 6.8 (32.3% of total length), width at spiracle 4.3, height taken posterior of eyes 3.0; snout round in dorsal and lateral views .

Nostrils very small, directed laterally, slightly leaning dorsally and anteriorly, openings circular; opening 0.6 from tip of snout; internarial distance (taken at internal edge of each nostril) 1.5; distance from narial opening to anterior edge of eye 0.7. Eyes directed dorsolaterally; eye length 0.8, width 0.7; interorbital distance from internal edge of each eye 1.6.

Spiracle sinistral 4.2 from tip of snout (61.5% of total length); inner wall free in its distal portion; length 0.8, width at base 0.6; opening directed dorsoposteriorly and with a diameter of 0.4. Vent tube totally bounded and dextrally to ventral fin, length 1.0, width 0.3; opening circular.

Tail length 14.3 (67.7% of total length); tail musculature narrowing gradually, tip pointed, reaching tail terminus; myotomes visible at distal half; muscle width at body-tail junction 2.2, muscle height 2.3; tail height at midtail 4.5; dorsal and ventral fin originate at body anterior to body-tail junction, but dorsal fin edge becomes evident at one third of tail lenght; dorsal fin height 1.3, ventral fin height 1.3; distal margin of tail pointed, subtly round. Lateral line system present; dorsal, middle body (only on body, not on tail), supraorbital, infraorbital and posterior infraorbital lines are distinguished, but not clearly.

Oral disc located ventrally, emarginated on both sides ( Fig. 10C); transverse width 1.9 (43.7% of body width); oral disc surrounded with 50 marginal papillae: 29 ventral papillae and 21 located laterally (10 at left side and 11 at right side); submarginal papillae absent; ventral marginal papillae aligned, but alternate papillae project to opposite directions; single anterior gap of papillae 0.8.

Anterior and posterior jaw sheaths serrated through their entire length; serrations less profound as they move away from center; anterior jaw sheath transverse width, including lateral processes, 0.9 (48% of oral disc width); anterior and posterior edge of anterior jaw sheath winding; posterior jaw sheath V-shaped, transverse width 0.4 (24% of oral disc width).

Labia tooth row formula 2(2)/3(1); anterior tooth row A-1 length 1.1, number of teeth 112; A-2 length 1.1, and 39 and 35 teeth at left and right side of gap, respectively; A-2 gap length 0.1; at P-1 gap 0.03; posterior tooth row P-1 length 0.9, 76 teeth (38 at each side of gap); P-2 length 1.0 and 86 teeth; P-3 length 0.7 and 76 teeth.

Color in preservative (~10% formalin). Dorsum, flanks and tail brown. Ventrally, a large brown blotch covers the region between the spiracle and the gut; venter translucent, leaving gut visible. Spiracle and vent tube translucent.

Tail musculature white, becoming translucent gradually until the tail terminus; brown spots scattered throughout the tail, this spots aggregate to form larger blotches, they are smaller and less intense posteriorly; tiny spots at the last portion of tail. Fins translucent, slightly brownish with the same spot pattern as tail.

Color in life. ( Fig. 11). Body light brown with golden glitter; a darker brown belt-like mark at tail-body junction. Tail cream with brown and golden spots, translucent posteriorly with smaller golden spots. Two conspicuous white marks on each side of oral disc and two on each side of body at spiracle level. These four mark visible in lateral and ventral view (QCAZ 33214–33215).

Variation. Forty two (42) tadpoles in Stages 25–4 were examined; however, not every stage is represented in the sample. Variation of 17 measurements is given in Table 9.

Hyloxalus italoi tadpoles exhibit the same color pattern in all developmental stages. Nonetheless, they become darker at latter stages. Lateral line system is evident in larger and darker tadpoles from Stage 25; dorsal, middle body, ventral, anterior, supraorbital, infraorbital, posterior infraorbital, anterior oral and longitudinal oral are visible. Dorsal blotches shown in adults are visible from Stage 39, being the interorbital mark the first to appear. One metamorph (Stage 43, QCAZ 33220ai) exhibits the V-shaped mark at scapular level and a very subtle posterior dorsum blotch; limbs are white with light brown transverse bars. The P-1 gap is absent in 50% of specimens in Stage 25 (n = 22) ( Table 9).

Comparisons. Hyloxalus italoi and H. yasuni are remarkably similar. However, H. italoi tadpoles are darker and generally exhibit large blotches with diffuse edges in body and tail, whereas H. yasuni tadpoles show dark stippling ( Figs. 14, 18). Furthermore, they differ significantly in their morphometric variables (MANOVA, p <0.001, F = 15.437, df = 30, df2 = 361.705, n = 137).

Hyloxalus italoi tadpoles differ from H. bocagei and H. maculosus tadpoles in morphometric variables (p <0.001). Hyloxalus italoi differs from H. bocagei in a lower body/tail proportion (t -test, t = -10.96, df = 108, p <0.001); tail musculature is more robust (t -test, t = -16.16, df = 108, p <0.001); body is more elongated; less marginal papillae (t -test, t = 9.58, df = 108, p <0.001); anterior edge of anterior jaw sheath is winding, round in H. bocagei ( Fig. 10); in vivo, H. bocagei has two pale pectoral spots and a mark at dorsal fin origin; whereas, H. italoi lack those marks but exhibit two pale marks at each side of oral disc and two at each side of body at spiracle level ( Fig. 11). Hyloxalus italoi differs from H. maculosus in that tail musculature reaches tail terminus (not reaching in H. maculosus ); dorsal tail blotch absent; spiracle directed dorsoposteriorly (laterally in H. maculosus ); blotches on labia (immaculate in H. maculosus ); less marginal papillae (t -test, t = 6.163, df = 63, p <0.001); anterior border of anterior jaw sheath winding (convex in H. maculosus ); in vivo, H. maculosus has only one pair of pale marks, one at each side of the oral disc ( Fig. 11).

Etymology. The specific name italoi is a patronym of Ítalo G. Tapia, collection manager of amphibian and reptiles at QCAZ. Ítalo G. Tapia is one of the collectors of specimens of the bocagei complex herein analyzed. He has also contributed significantly to the growth of scientific collections since 2000, hence, to the development in Herpetology in Ecuador.

Comments. Hyloxalus italoi is strikingly similar to H. yasuni ; however, genetic distance between these species is very high (4.9–5.7% in mitochondrial genes 12S, 16S and Cytochrome b; Tables 2 and 3, Santos 2002, Santos et al. 2009: Fig. S3C). Moreover, tadpoles differ in coloration pattern and morphometric variables (see Comparisons between tadpoles), and their advertisements call show differences in temporal and spectral parameters (see Calls Descriptions and Comparison section). Therefore, they are considered not to be conspecific. Further information is included under Phylogeny and Chronogram and Ancestral Area Resconstruction sections ( Tables 2 and 3; Fig. 1).

Referred specimens from Santiago (Provincia Morona Santiago, Ecuador) and Río Cenepa (Departamento Amazonas, Peru) are morphologically similar to type specimens and are included as Hyloxalus italoi ( Table 8). Specimens from Santiago are closely related to Hola Vida (Provincia Pastaza) specimens in the molecular phylogeny. Nonetheless, genetic distance between both populations is high as well (3.8–4% in mitochondrial genes 12S, 16S and Cytochrome b; Tables 2 and 3, Fig. 1; Santos et al. 2009: Fig. S3C). Thus, it is conceivable that they do not belong to the same species. Given the absence of molecular data for Cenepa specimens, they are assigned as referred specimens of H. italoi for their morphological similarity with specimens of Reserva Hola Vida and geographic proximity with specimens from Santiago.

Santos et al. (2003, 2009) assigned the name Hyloxalus maculosus to specimens from El Porvenir (= Reserva Hola Vida) and Kapawi, Provincia Pastaza, which belong to H. italoi . Their assigment was done on the basis of the proximity of Reserva Hola Vida specimens to the type locality of H. maculosus (Puyo, Provincia Pastaza).