Hyloxalus bocagei ( Jiménez de la Espada 1871 )

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 : 11-26

Hyloxalus bocagei ( Jiménez de la Espada 1871)

Hyloxalus bocagei — Jiménez de la Espada, 1871:59.— Syntypes: MNCN 1583–84 “Hab. in Ecuador; ad sylvas pagi S .

Jose de Moti men. Jun. nobis invento” [Cantón Quijos], Provincia Napo, Ecuador [collected in June 1865], MNCN

1583 designated lectotype by Coloma (1995). Adult, possibly female (SVL = 26.6; Fig 2). Hylixalus bocagii — Boulenger 1882:138. Colostethus bocagei — Edwards 1971:148. Hyloxalus bocagei — Grant et al. 2006:168.

Diagnosis. A species with (1) mean SVL in adult males 22.8 mm (20–25 mm, SD 1.3 mm, n = 23) and in adult females 27.2 mm (23.6–29.5 mm, SD = 1.6, n = 21); (2) disc of Finger IV expanded 1.5–2 times the width of adjacent phalange; (3) Finger II shorter than Finger III; (4) fringes present on fingers; (5) disc of Toe IV expanded 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—(1½–2 +) II (1–1½)—(2–3 -) III (1–2)—(2½–3½) IV (3–3½)— (1–2) V; (9) oblique lateral stripe present, complete or sometimes diffuse anteriorly; (10) dorsum with scattered grayish brown marks; (11) gular-chest region uniformly gray in adult males, gray with white dots in adult females; (12) venter uniformly gray in adult males, white and slightly translucent in adult females; (13) sexual dimorphism in ventral coloration present; (14) tadpoles uniformly brown with a conspicuous longitudinal brown mark on dorsum of tail musculature and, in vivo, two ventral silver marks on anterior portion of body; (15) tadpole spiracular opening oriented dorsoposteriorly; (16) call is a long trill composed of paired pulsed notes.

Hyloxalus bocagei is similar to species that have extensive toe webbing and oblique lateral stripe complete, sometimes diffuse anteriorly ( H. fuliginosus and some specimens of H. maculosus ). It is distinguished from H. fuliginosus by its smaller size ( H. fuliginosus , female SVL 27.8–32.5 mm, mean = 29.9 mm, n = 12, U-Mann-Whitney, U = 22, p <0.001; male SVL 23.6–24.3 mm, mean = 23.8 mm, n = 4, U- Mann-Whitney, U = 27, p> 0.001) and by having more extensive toe webbing (see Coloma, 1995:23). Hyloxalus bocagei differs from H. maculosus by the dorsal coloration pattern ( Figs. 3 and 4). Hyloxalus maculosus has a big blotch at sacrum level, whereas H. bocagei has several small and irregular blotches in the posterior dorsum. Occasionally, the oblique lateral stripe is diffused anteriorly; when this happens, it is similar to H. sordidatus Duellman , whose oblique lateral stripe is present in the posterior half of the flanks. Nonetheless, H. sordidatus has larger size (male SVL 24.2–29.9 mm, mean = 25.7, n = 8, t -test, t = 4.84, df = 25, p <0.001; females SVL 31.8–36.1 mm, mean = 33.6 mm, n = 3, t -test, t = 6.67, df = 22, p <0.001) and the gular region is yellow in females ( Duellman 2004).

Description. (n = 44: 23 males, 21 females). Morphometric variation is depicted on Table 4. Head slightly longer than wide; snout subacuminate in dorsal view, round or angular in lateral view; loreal region slightly concave; nostrils protuberant; supratympanic bulge covering upper edge of tympanum.

Finger II shorter than Finger III; fingers unwebbed; fringes discreet; terminal discs expanded 1.5–2 times the width of adjacent phalange; subarticular tubercles round, those of the Fingers II and III slightly oval, the more distal tubercles in Fingers IV and V only visible under dissecting microscope; outer metacarpal tubercle large, round and slightly protuberant; inner metacarpal tubercle at the base of the thumb, small, elliptical and slightly protuberant. Outer metatarsal tubercle present; inner tarsal fold sigmoid present on distal half of tarsus; outer metatarsal tubercle round; inner metatarsal tubercle smaller than outer, elliptical; protuberance present between the two metatarsal tubercles, similar to a tubercle in appearance, present in 96% of specimens (n = 23); toes more than a half webbed, webbing formula I 1—(1½–2 +) II (1–1½)—(2–3 -) III (1–2)—(2½– 3½) IV (3–3½)—(1–2) V; lateral fringes extensive; terminal discs expanded, less than those of fingers, 1.5 times the width of adjacent phalange; subarticular tubercles round, small; supernumerary tubercles absent.

Skin of dorsum, limbs, flanks and venter smooth; scattered tubercles posterior to the sacral region and on flanks of some specimens, especially near the oblique lateral stripe (QCAZ 32386, 32389, 32392, 37257– 37260); round tubercle posterior to the mandible junction; anal sheath conspicuous. Tongue twice as long as wide, thinner and broader posteriorly, posterior half not attached to mouth’s floor. Testes white.

Color variation in preservative. (~70% ethanol). Variation in color patterns is depicted on Figs. 5A – 7A. Dorsum of head and body dark brown, slightly grayish; an interorbital blotch, another V- shaped blotch at scapular level and, small blotches scattered on the posterior region of dorsum; flanks brown, white spotted; a diffuse dark brown stripe from the anterior tip of snout, through loreal and supratympanic regions, to the armbody junction. Oblique lateral stripe present from groin to the posterior corner of eye, sometimes diffused anteriorly (e.g. QCAZ 32390), sometimes interrupted (e.g. QCAZ 37260). Forelimbs brown with transverse bars darker in forearm, a longitudinal stripe on anterior surface of arm from elbow to arm-body junction; dorsal surfaces of hind limbs brown with darker transverse bars (9–11 in leg and tarsus); ventral surface of hind limbs gray in males, cream in females. Venter gray in males, white in females; gular-chest region uniformly gray in males, white-dotted in females; axillar region translucent. Palmar and plantar surfaces gray; toe webbing cream.

Fourteen juveniles (QCAZ 5005, 9016, 15199–15200, 18350, 18625, 20826, 32389, 32395–32396, 37621–37623, 37627) with SVL 12–22.6 mm (mean = 16.2 mm and SD = 3.4) have the same coloration of adult specimens. However, the transverse bars on hind limbs are more conspicuous, and some of the specimens (n = 6, QCAZ 6896, 17938, 20826, 32389, 32395–32396) exhibit white tubercles on dorsum, flanks and dorsal surfaces of limbs. Ventrally, they exhibit ontogenetic variation; the youngest juvenile are translucent but acquire a cream coloration as development proceeds. Eight recently metamorphosed specimens (QCAZ 8565, 10259, 10328, 10926, 37494, 37650, 37656–37657) have SVL of 9.6–12.5 mm (mean = 11.6 and SD = 0.97).

Color in life. QCAZ 32385 (male with back-riding tadpoles, Figs. 3A, 8A). Iris golden with small black flecks. Dorsum olive-brown with dorsal blotches dark brown and flanks with a dark brown stripe. Oblique lateral stripe extended from anterior corner of the eye to the groin, with cream and golden traces, olive-tan anteriorly, with appearance of two small golden glands at each side of the eye. Tympanum cream in coloration. Mandibular tubercle iridescent cream. Dorsal surfaces of fore and hind limbs olive-brown with a pale blotch on the dorsal surface of the arms, near the arm-body junction. Ventral surfaces uniformly gray (MIP field notes, 18 September 2006).

QCAZ 32390 (adult female, Fig. 4A). Coloration similar to male QCAZ 32385 . Posterior dorsum and dorsal surfaces of limbs slightly coppery with a light yellow spot at arm-body junction. Oblique lateral stripe cream, slightly coppery at the posterior corner of eye, and golden at groin. Ventral surfaces iridescent white and limbs translucent with dark stippling ( MIP field notes, 18 September 2006) .

Variation. Specimens from La Virgen, 2 km West to Volcán Reventador (n = 9, QCAZ 20824–20826, 37257–37260, 37627–37628), exhibit dorsum light gray and dorsal blotches and oblique lateral stripe are more contrasting than those specimens previously described. An adult female (QCAZ 37260) has a white gular-chest region with light gray blotches. Postmandibular tubercle white. Inner tarsal fold reaches one third of tarsus in six of these specimens (QCAZ 20825, 37257, 37259–37260, 37627–37628).

Tadpole. The following description is based on a specimen in Stage 28 ( QCAZ 32404 a, Figs. 9A–C). Tadpole corresponds to a series of ten back-riding tadpoles of adult male QCAZ 32385 (see also Ecology and Distribution sections), obtained in Río Leo , trail to Cascada San Rafael , 200 m from Quito-Lago Agrio road, Provincia Sucumbíos, Ecuador. All measurements provided below are in millimeters. Total length 17.7; body ovoid, depressed, slightly narrower at posterior third; body length 7.0 (39% of total length), width at spiracle 4.8, height taken posterior of eyes 3.2; snout round in dorsal and lateral views .

Nostrils small, directed anterolaterally, openings circular; opening 1.1 from tip of snout; internarial distance (taken at internal edge of each nostril) 1.3; distance from narial opening to anterior edge of eye 0.6. Eyes directed dorsolaterally; eye length 0.8, width 0.7; interorbital distance from internal edge of each eye 1.4.

Spiracle sinistral 4.3 from tip of snout (61.4% of total length); inner wall free in its distal portion; length 1.0, width at base 1.0; opening directed dorsoposteriorly and with a diameter of 0.5. Vent tube totally bounded to ventral fin, length 1.0, width 0.6; opening circular and dextrally to ventral fin.

Tail length 10.5 (59.4% of total length); tail musculature narrowing gradually, tip pointed not reaching tail terminus; myotomes visible through the length of musculature, more differentiated posteriorly; musculature width at body-tail junction 1.7, musculature height 2.0; tail height at midtail 4.2; dorsal and ventral fin originate at body-tail junction; dorsal fin height 1.3, ventral fin height 1.0; distal margin of tail round. The lateral line system is present. The infraorbital, supraorbital, and middle body lines were hardly identifiable.

Oral disc located ventrally, emarginated on both sides ( Fig. 10A); transverse width 2.1 (43.9% of body width); labia surrounded with 72 marginal papillae: 49 ventral papillae and 23 located laterally (11 at one side and 12 at the other); submarginal papillae absent; ventral marginal papillae aligned, but alternate papillae project to opposite directions, emulating two rows; this orientation is more pronounced toward the sides of the oral disc; single anterior gap of papillae 1.3.

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 (42.9% of oral disc width); anterior edge of anterior jaw sheath convex; posterior edge, winding; posterior jaw sheath V- shaped, transverse width 0.7 (35.7% of oral disc width).

Labia tooth row formula 2(2)/3; anterior tooth row A-1 length 1.5, number of teeth 110; A-2 length 1.6 and 49 teeth at each side of gap; A-2 gap length 0.2; at P-1 row, teeth proximal to center converge orientating to the front; posterior tooth row P-1 length 1.5, 96 teeth (48 at each side of small gap); P-2 length 1.6 and 102 teeth; P-3 length 1.6 and 110 teeth.

Color in preservative. (~10% formalin). Dorsum and flanks uniformly dark brown. Ventrally, oral disc and immediate posterior region translucent; posterior labium with six blotches scattered at proximal portion, near the body junction. Anterior region of spiracle stippled; posterior region of venter translucent leaving gut visible. Spiracle and vent tube translucent. Jaw sheath coppery brown with metallic glitter.

Tail dorsally and ventrally white, translucent posteriorly with a conspicuous dorsal brown mark extending from the body-tail junction to tail terminus ( Figs. 9A–B). Ventral brown mark from midtail to terminus. Laterally, brown blotches throughout entire extension. Dorsal, ventral, and lateral marks decrease their size and intensity gradually to tail terminus. Fins translucent; dorsal fin with scattered spots, decreasing in size and intensity and increasing in number gradually towards terminus; small spots at posterior half of ventral fin.

Color in life. ( Fig. 11). Dorsum brown, golden glittered; tail pinkish with brown and golden spots in the dorsoanterior portion. Ventrally translucent, two very conspicuous silver marks at anterior portion. A golden mark on dorsal fin, just posterior to its origin (photo of QCAZ 32252, taken by LAC).

Variation. Eighty three (83) tadpoles in Stages 25–36 were examined; however, not every stage is represented in the sample. Variation (i.e., sample size, mean, SD, and range) of all 17 measurements is given in Table 5.

Variation in tooth row P-1 consists in that 50% of tadpoles in Stages 25, 26 and 27 (n = 71) have the same projection of teeth as specimen QCAZ 32404a. Three specimens in Stages 25, 26 and 27 exhibit an evident gap in this row. From Stage 31, gap is present in every specimen examined. Labial papillae oriented to opposite sides, can diverge at its base, forming two rows of papillae. Lateral papillae can also acquire the orientation previously described. One tadpole in Stage 35 (QCAZ 17769) exhibits evident middle body and dorsal lines of lateral line system; middle body is relatively dorsal to body, located near dorsal line.

One metamorph in Stage 43 (QCAZ 18753) exhibits the same dorsal color pattern than adults; limbs are white with light brown transverse bars; ventrally translucent.

Comparisons. Tadpoles of Hyloxalus bocagei are notably similar to H. maculosus and H. sauli . Nevertheless, they differ from H. maculosus in (1) shape of dorsal fin ( Figs. 9B, 11A–B, 19B); (2) spiracular opening directed dorsoposteriorly (directed laterally in H. maculosus ); (3) oral disc wider (t -test, t = -3.544, p = 0.001); (4) stippling on anterior and posterior labia (labia immaculate in H. maculosus ); (5) anterior jaw sheath slender ( Fig. 10A–B). It differs from H. sauli in the following: (1) tail musculature is thicker and reaches tail terminus in H. sauli ; whereas, it is slender and does not reach tail terminus in H. bocagei ; (2) tail terminus is pointed in H. sauli , round in H. bocagei ; (3) proximal third of dorsal fin is very thin in H. sauli ; (4) H. sauli has less brown marks, specially on tail; (5) anterior edge of anterior jaw sheath is slightly winding in H. sauli , whereas it is round in H. bocagei . Oral discs are very similar between both species.

Tadpoles of Hyloxalus bocagei are morphometrically different to H. italoi and H. yasuni (MANOVA, F = 15.437, df1 = 30, df2 = 361.705, p <0.001, n = 137). Additionally, the following differences are appreciable: (1) H. bocagei is smaller (t -test, t = -10.75, df = 108, p <0.001 with H. italoi ; t = -3.4, df = 82, p <0.001, with H. yasuni ); (2) body/tail proportion is lower in H. bocagei (t -test, t = -10.96, df = 108, p <0.001 with H. italoi ; t = -7.3, df = 82, p <0.001, with H. yasuni ); (3) tail musculature is thinner in H. bocagei (t -test, t = -16.16, df = 108, p <0.001 with H. italoi ; t = -7.07, df = 82, p <0.001, with H. yasuni ); (4) eyes are smaller in proportion to body size in H. bocagei (t -test, t = -12.33, df = 108, p <0.001 with H. italoi ; t = -6.1, df = 82, p <0.001, with H. yasuni ); (5) body is less elongated in H. bocagei ; (6) greater number of labial papillae (t -test, t = 9.58, df = 108, p <0.001 with H. italoi ; t = 7.08, df = 82, p <0.001, with H. yasuni ); (7) anterior edge of anterior jaw sheath is round in H. bocagei , winding in H. italoi and H. yasuni ( Fig. 9); (8) in life, H. bocagei has two pale spots at anterior portion of venter, just posterior to oral disc, and a small mark at body-tail junction, H. italoi and H. yasuni exhibit two pale marks on each side of oral disc and two on each side of body at spiracular level ( Fig. 11).

Morphometric evaluation of type material. A PCA was performed with 347 specimens belonging to the bocagei clade and two syntypes of Hyloxalus bocagei housed at MNCN. Three components with eigenvalues greater to 1.0 were extracted. These axes accounted for 69.7% of total variation. Head variables had high loadings on PC I and limb variables on PC II, respectively. Internarial distance (IND) and eye length (EL) had high loadings in PC III. Arm length (ARM) crossloaded on the two first components, and eye length (EL) on the three components. The two syntypes of H. bocagei were located on the left superior quadrant, in a biplot of the first two components ( Fig. 12A). Therefore, those specimens would be similar to specimens with long limbs and small head located on the same quadrant, particularly those of the surroundings of Volcán Reventador (designated as H. bocagei herein).

In the DFA, the two syntypes were classified as Hyloxalus bocagei (sensu this paper) ( Fig 12B, Table 6). The first two DF had eigenvalues greater than 1.0 and explained 93.9% of total variation. Along the DF 1, the highest loadings were for arm length ( ARM). Along DF 2, the highest loadings were for head width ( HW) and eye-nostril distance ( END). The two syntypes are located near H. bocagei in the morphometric space; moreover, one of them is next to the group centroid .

Comments. The type locality of Hyloxalus bocagei is the jungle of the village of San José de Moti, cantón Quijos, Provincia Napo, Ecuador ( Jiménez de la Espada, 1871:59). This village is located at the northwestern slopes of Volcán Sumaco according to Jiménez de la Espada et al. (1998) and Savage (1978). However, at this time there is no locality under that name in the area and the exact altitude and location remains unknown. According to Jiménez de la Espada, indigenous people gave him dead frogs and snails in exchange of medallions during his stay in this village ( Jiménez de la Espada et al. 1998:174). This report complicates confirmation of the collection site of this species, as it is unknown whether the indigenous collected the frogs in San José or in its surroundings.

The type material is in poor condition; therefore, a description of those specimens is not useful because very few external diagnostic characters can be described ( Fig. 2). Herein, we described a series from the surroundings of Volcán Reventador (Río Leo, trail to the Cascada San Rafael, 200 m from Quito-Lago Agrio road, Provincia Sucumbíos, Ecuador). This population is considered Hyloxalus bocagei due to its morphometric resemblance with the type specimens, its occurrence near the type locality and its sympatry with H. fuliginosus (see Coloma, 1995:23).

The specimen designated as paratype of Hyloxalus maculosus (MCZ-A 104846, Fig. 16) by Rivero (1991) corresponds to H. bocagei . The specimen MCZ-A 194846 was collected on Río Reventador, trail to the Cascada San Rafael and exhibits several small blotches in the posterior dorsum, a conspicuous oblique lateral stripe and the morphometric profile of H. bocagei specimens ( Fig. 16). Further information is included under Phylogeny and Chronogram and Ancestral Area Resconstruction sections ( Tables 2 and 3; Fig. 1).