Dryadobates erythropus, Grant & Pinheiro, 2025

Grant, Taran & Pinheiro, Paulo Durães Pereira, 2025, A recently extinct new species of Dryadobates (Anura: Aromobatidae) from South Brazil: species description and implications for the historical distribution and recent extinction history of the clade, Zootaxa 5693 (4), pp. 583-595 : 586-589

Dryadobates erythropus sp. nov.

ZooBank LSID: urn:lsid:zoobank.org:pub:

( Fig. 1 ; Table 1 )

Holotype. USNM 148487 , adult male collected at Tarumã , Curitiba, Paraná, Brazil, 9 January 1963, by Doris H. Blake and Doris M. Cochran.

Etymology. Like the specific epithets alagoanus , capixaba , and carioca , erythropus refers to inhabitants of the region of the type locality. Specifically, it is derived from the Greek erythros (red) and pous (foot), Latinized as pus, from the Portuguese term pé-vermelho (red-foot), a colloquial nickname for people in rural areas of Paraná, originating from the farmers who often worked barefoot on the characteristic red soil of the northern part of the state.

Generic placement. We place the new species in Dryadobates on the basis of the morphology of its digital discs (finger discs II, IV, and V unexpanded), absence of a metatarsal fold, presence of a complete pale oblique lateral stripe, absence of a pale dorsolateral stripe, presence of basal toe webbing between toes III–IV and absence between all other toes, presence of pale paracloacal marks, and small size ( Grant et al. 2025).

Definition. A small species of Dryadobates (adult male SVL 13.5 mm, females unknown); testes of adult males unknown; throat of adult males immaculate; distal subarticular tubercle absent on finger V; inner metatarsal tubercle approximately same size as outer metatarsal tubercle, well separated from subarticular tubercle of toe I; toes II–III free of webbing; pale oblique lateral stripe complete, solid, discrete, well defined along entire length (i.e., not diffuse or narrow and faint anteriorly).

Diagnosis. Dryadobates erythropus sp. nov. differs from all nominal congeners in possessing a conspicuous pale oblique lateral stripe that is discrete and well defined along its entire length (anteriorly indistinct in D. alagoanus , D. bokermanni , D. capixaba , D. carioca , D. lutzi , and D. olfersioides ). It further differs from all congeners except D. olfersioides in lacking melanophores on the throat of adult males. It differs from D. olfersioides in being much smaller (adult male SVL 13.5 mm in D. erythropus sp. nov., 17.0– 18.8 mm in D. olfersioides ; Table 1 ). Dryadobates erythropus sp. nov. further differs from D. capixaba , D. carioca , and D. olfersioides in lacking basal webbing between toes II–III, D. lutzi in presenting the inner metatarsal tubercle approximately the same size as outer metatarsal tubercle, well separated from subarticular tubercle of toe I (inner metatarsal tubercle elongate, up to ca. 2–3× longer than outer metatarsal tubercle, almost reaching subarticular tubercle of toe I in D. lutzi ), and D. bokermanni and D. carioca in smaller adult male SVL ( 14.9–17.9 mm in D. bokermanni ; 14.6–16.1 mm in D. carioca ; Table 1 ).

Measurements of holotype (mm). SVL 13.5, FAL 3.5, H 3.7, TL 6.3, HW 3.9, HL 4.0, EL 1.9, EN 1.2, N 1.9, SL 1.9, IOD 1.7, TYM 1.0.

Holotype description. Adult male 13.5 mm SVL; left vocal slit present, tissue too badly desiccated and fragile to probe for right vocal slit; testis and large intestine pigmentation undetermined. Ventral and most dorsal surfaces smooth; exposed surface of shank and posterior dorsum with low, inconspicuous granules. Postrictal and cloacal tubercles absent. Head width 29% of SVL and 98% of diagonal HL. EL 48% of HL. Snout artifactually concave (due to desiccation) in dorsal view ( Fig. 1A ), SL 48% of HL (presumably longer prior to desiccation). Nares slightly flared, directed posterodorsad, EN 63% of EL and 63% of SL. Loreal region weakly concave, almost vertical. Canthus rostralis well defined, sharply rounded. Tympanic ring strongly defined externally along anteroventral half of tympanum. Tympanum directed posterodorsad, TYM 53% of EL. Supratympanic bulge associated with the underlying depressor musculature present.

Hand length 27% of SVL, 1.06 times FAL. Relative finger lengths IV > II > III > V ( Fig. 1E ). Finger II 1.1 times longer than finger III. Fingers too fragile to appress, finger III estimated to reach middle of distal subarticular tubercle of finger IV, finger V estimated to reach just past distal edge of basal subarticular tubercle of finger IV. Phalangeal swelling on finger IV of adult males present, dorsal and preaxial only, conspicuous, absent elsewhere on hand. Hand tubercles well defined, protuberant. Fingers II, III, and V each with a single subarticular tubercle; finger IV with two subarticular tubercles; hyperdistal subarticular tubercles absent. Thenar tubercle elliptical, palmar tubercle round. Fringes absent. Metacarpal fold absent. Discs unexpanded (state 0 of Grant et al. 2006), all bearing paired dorsal scutes. Carpal pad and black arm gland absent.

Tibia length 47% of SVL; FL not measured due to fragility of toe IV. Relative lengths of toes IV > III > V > II > I ( Fig. 1F ). Foot tubercles well defined, protuberant. Inner metatarsal tubercle approximately same size as outer metatarsal tubercle, well separated from subarticular tubercle of toe I. Toes I and II with one subarticular tubercle each, toes III and V with two, toe IV with three. Webbing absent between toes I– II, II – III, and IV – V, rudimentary webbing present between toes III – IV, giving formula III 3–4 IV. Fringes absent. Metatarsal fold absent. Tarsal keel well defined, short, strongly curved, tubercle-like, not extending from metatarsal tubercle, lying one-third of tarsal length from inner metatarsal tubercle. Discs bearing paired dorsal scutes; discs badly desiccated, but discs I and V estimated to be unexpanded (state 0 of Grant et al. 2006), disc II weakly expanded (state 1), discs III and IV moderately expanded (state 2).

Color in preservative ( Fig. 1 ). Dorsum tan with dark brown stippling and blotches. Dorsolateral stripe absent. Flank uniformly dark brown, bisected by conspicuous cream oblique lateral stripe, extending from groin to posterior edge of eyelid (i.e., not extending along canthus rostralis), well defined along entire length, not becoming diffuse or narrow and faint anteriorly. Pale ventrolateral stripe not discernible (i.e., iridophores absent and not delimited ventrally by brown stippling) but inferred to have been present in life based on well-defined ventral edge of dark brown flank coloration and occurrence above arm insertion, ventral half of tympanum, and around snout (i.e., continuous with pale stripe along upper lip); surface below pale upper lip stripe with sparse melanophores. Otic region same color as flank, bordered above by pale oblique lateral stripe and below by pale ventrolateral stripe; tympanum blackish brown dorsally, cream (from ventrolateral stripe) ventrally. Dark color of flank and otic region continuing from anterior corner of eye along loreal region above pale upper lip, through nares to tip of snout. Throat, chest, and belly immaculate. Lower lip immaculate. Ventral surfaces of arm pale yellow, lacking melanophores; anterior and posterior surfaces of upper arm with longitudinal brown stripe; dorsal surfaces with pale brown stippling, even on upper arm, forming irregular pale spotting on forearm. Dorsal surfaces of outer fingers stippled pale brown, inner fingers with less stippling. Palmar surfaces pale yellow with faint brown stippling. Exposed surfaces of thigh, shank, and foot with irregular pale brown stippling. Anterior surface of thigh dark brown; posterior surface of thigh dark brown with miniscule pale spots posteroventrally; pale paracloacal mark well defined. Ventral surface of thigh and concealed surfaces of shank and foot pale yellow. Plantar surfaces pale yellow with brown stippling.

Color in life. Unknown.

Advertisement call. Unknown.

Tadpoles. Unknown.

Geographic distribution. The only known specimen of Dryadobates erythropus sp. nov. was collected in 1963 in Tarumã, Curitiba, PR ( Fig. 2 ).

Conservation status. Currently, the type locality of Tarumã is a highly developed, mixed residential and commercial neighborhood in the city of Curitiba that lacks appropriate habitat for Dryadobates spp. Although many other localities in Paraná have been sampled over the past six decades (summarized by Santos-Pereira et al. 2018), there are no additional records of this or any other dendrobatoid frog in the state. As such, we presume this species to be extinct ( IUCN 2012).

Remarks. The single known specimen of Dryadobates erythropus sp. nov. is badly desiccated and extremely brittle. Soil and grains of sand are adhered to the integument. The mandible is broken on the right side, left finger IV is broken (but still attached), the right knee is barely attached to the shank, right toe IV is broken (but still attached), the distal portion of left toe V is missing, and the left leg is partially detached from the pelvic girdle. Given the fragility of the specimen, we did not attempt to examine testis or large intestine pigmentation or straighten left toe IV for measurement.

Figures

FIGURE 1. The highly desiccated adult male holotype of Dryadobates erythropus sp. nov. (USNM 148487), showing (A) dorsal, (B) ventral, and (C) lateral (right) views of body, (D) lateral (left) view of head, (E) palmar view of right hand (note phalangeal swelling of finger IV, sensu Cavalcanti et al. 2022), and (F) plantar view of left foot. Scale bars: A, B, C: 3 mm; D, E, F: 1 mm.

FIGURE 2. Distribution of the southernmost species of Dryadobates in the Atlantic Forest of southeastern Brazil, including D. erythropus sp. nov. and named and unnamed species. The expanded satellite image shows the type locality of Tarumã (star) within the urban area of present-day Curitiba.