Ischnocnema penaxavantinho, Giaretta, Ariovaldo Antonio, Toffoli, Daniel & Oliveira, Luciano Elias, 2007

Giaretta, Ariovaldo Antonio, Toffoli, Daniel & Oliveira, Luciano Elias, 2007, A new species of Ischnocnema (Anura: Eleutherodactylinae) from open areas of the Cerrado Biome in southeastern Brazil, Zootaxa 1666, pp. 43-51 : 44-49

Ischnocnema penaxavantinho sp. n.

( Figs. 1–2 above, 3C–D, 4 above)

Holotype. Adult male ZUEC 13639 ( Figure 2 above left). Estação Ecológica do Panga (around 19º11’S; 48º24’W) municipality of Uberlândia, state of Minas Gerais, Brazil. Collected by A. A. Giaretta on 4 Oct. 2001.

Paratopotypes. Thirteen adults. Five males ZUEC 13640–44, collected from 28 Sep. 2000 to 4 Oct. 2001; five females ZUEC 13645–49, collected from 15 Nov. 2000 to 22 Feb. 2001; three males AAG-UFU 4122–4, collected from 2 to 9 Nov. 2006. All ZUEC specimens collected by A. A. Giaretta; AAG-UFU specimens collected by H. C. M. Costa and A. A. Giaretta.

Diagnosis. Males (topotypes) of Ischnocnema penaxavantinho sp. n. (14.9–18.7 mm SVL, Table I) are smaller than those of I. juipoca (19.1–20 mm; Table I; Figures 3–4 above), I. octavioi (29.0–34.0 mm), E. heterodactylus (Miranda Ribeiro) (25.0 mm), P. dundeei (22.0–27.0 mm), and P. crepitans (31.0 mm). Ischnocnema verrucosa is coarsely tuberculate on the dorsal surfaces ( Lynch 1972; Caramaschi & Canedo 2006), while the new species is mostly smooth. Different from P. crepitans and E. heterodactylus , specimens of the new species do not have expanded discs on finger III and IV. Pristrimantis crepitans does not have marked sexual dimorphism in size ( Heyer & Muños, 1999), a feature present in I. penaxavantinho sp. n.. Nuptial pads and finger/toes discs are present in P. dundeei ( Padial & De La Riva, 2005) and absent in the new species. Different from the new species, I. verrucosa is primarily a forest dweller (C. Canedo, pers. com.), as are P. dundeei and I. octavioi . The advertisement call of the new species has more (1.5–2.5 times) pulses and higher (1.3–1.8 times) pulse repetition rate than that of I. juipoca (see call description sections).

Description of the holotype. Adult male ZUEC 13639. Head wider than long; rostrum subacuminate in dorsal view, round in profile; nostrils closer to the snout tip than eye; canthus rostralis rounded; loreal region concave; upper eyelid with 3–4 enlarged tubercles; supratympanic fold defined, obscuring the superior and posterior edges of tympanic annulus; a discrete thin dermal fold from between nostrils to vent; tympanic membrane and tympanic annulus distinct; tympanum higher than wide, widest diameter 1/3 of eye diameter; 1–2 rounded postrictal tubercles at each side of head; choanae oval, not concealed by palatal shelf of maxillary arch; vomerine odontophores almost indistinct, posteromedian oblique, and lacking teeth; tongue longer than wide, oval, its posterior border not notched, posterior 1/4 free; vocal slits posterolateral to tongue; vocal sac developed, subgular; belly skin smooth; inner metacarpal tubercles oval; half the size of the outer; up to 4 supernumerary tubercles; subarticular tubercles rounded; when aligned finger 1~2<4<3; tips of fingers III and IV slightly expanded, lacking grooves or pads; no nuptial pads; skin of dorsal surfaces (head, back, flanks, and legs) smooth with scattered smooth tubercles; inner and outer metatarsal tubercles rounded, nearly of same size; 0–2 plantar supernumerary tubercles at the base of toes; subarticular tubercles of toes round, subconical; toes lacking fringes; relative length of toes 1<2<5<3<4; tips of toes III and IV slightly expanded, lacking grooves or pads. Measurements (mm) and proportions (%) in relation to SVL (14.9 mm) are: head width (HW) 5.8 (38.9); head length (HL) 5.5 (36.9); eye-eye distance (EE)1.6 (10.7); eye-nostril distance (EN) 1.3 (8.7); tibia 7.7 (51.7); femur 7.6 (51.0); foot 8.2 (55.0); maximum width of forth toe tip (4TT) 0.5 (3.7); maximum width of third finger tip (3FT) 0.5 (3.7); maximum vertical tympanum diameter (TD) 0.75 (5.0). In preservative, dorsal surfaces dark brown with nearly circular darker grey spots on tubercles; mottling on lips dark brown; belly dark cream; vocal sac dark grey. Variation in measurements in the type series in Table I; in preservative, individuals can be dark grey on dorsal surfaces and have a black vocal sac.

Advertisement call (from one topotype). Figure 5A–B. Call duration 520–650 ms; frequency range and sound energy increasing from the beginning to the middle of the call; 15–18 pulses/call; pulse repetition rate 23–29/s; dominant frequency peak at 3800 Hz; last pulse lasting 2–10 ms, inter-pulse intervals 40 ms; call repetition rate 6.6 calls/min. Calls heard in the field were emitted in series of 1–5, spaced about 7–22 s from each other; call series spaced by 5–20 minutes.

Natural history. The vegetation at the type locality (Panga) includes several Cerrado ( Oliveira & Marquis 2002) physiognomies, including “Veredas” (a vegetation dominated by grass-like plants, with dispersed bushes and Mauritia flexuosa palms) and a riverine forest running along the Panga River (2 m wide). Human altered areas are covered by the exotic grass Brachiaria sp.. The local weather presents a hot and wet summer (Sep.–Mar.), and a cold and dry winter (Apr.–Aug), when frosts may occur. The annual precipitation is around 1500 mm ranging from 750 to 2000 mm ( Giaretta & Kokubum 2004). Males were heard calling on the ground (N = 2) or perched (up to 60 cm height) (N = 3) amidst dense tufts of natural grass-like herbs in Veredas or on Brachiaria sp. up to 200 m from permanently wet soil (N = 1). Rarely, when fires cleared open areas from grasses, males were heard also from within forests or forest borders (N = 5). Calling activity was observed (Oct.-Mar.) being most intense during afternoon and the first hours of the night.

Etymology. The specific epithet is an arbitrary fusion of two Portuguese words pena (meaning feather) and xavantinho (meaning little Xavante, a group of pre-colonization natives). These names were used by two regional singer brothers (Pena Branca and Xavantinho) who in their songs emphasized the beauty of the Brazilian nature and the countryside way of life. It is used as a noun in apposition and as homage to both artists.

Variation. We tentatively attribute specimens collected (AAG) in Perdizes to the new species ( Figure 2 below). The three analyzed specimens (AAG-UFU 2463, 2575, 2616) presented a mean SVL of 19.5 mm (SD = 0.87), significantly larger than the topotypic population (ANOVA F1, 6 = 11.8; p <0.02). Advertisement call (Figure 5C): Duration 810–960 ms; frequency range and sound intensity rising from the beginning to the first third of the call; 17–19 pulses/call; pulse repetition rate 20/s; dominant frequency peak at 3500 Hz; last two pulses lasting 4.2–4.6 ms, 50–70 ms interval; 3 calls/min. The call of a second male (EleuthpenaxavMG2AAGb) lasted 850 ms, had 17 pulses/call, and 2 calls/min. (19:00h; 20.5 o C).

In comparison to the new species, advertisement calls of Ischnocnema juipoca show the following parameters (see also Sazima & Cardoso 1978; Haddad et al. 1988). One topotype recorded (Figure 5D). Call duration 510 ms; frequency range and sound energy increasing from the beginning to the middle of the call; 8 pulses/call; pulse repetition rate 16/s; dominant frequency peak at 3300 Hz; last pulse lasting 20 ms, interpulse intervals 50 ms; calls released sporadically. This call is shorter, has fewer pulses, and lower pulse repetition rate than that of I. penaxavantinho sp. n. (Figure 5A–B).

FIGURE 5. Advertisement call of two closely related species of Ischnocnema . A—Oscillogram, B—spectrogram of the call of a topotype Ischnocnema penaxavantinho sp. n., voucher AAG-UFU 4123, 9 November 2006, 18:15h, Uberlândia (MG), air 22.9 o C, record file EleuthpenaxavMG3AAGm. C— Spectrogram of the call of species tentatively attributed to I. penaxavantinho sp. n., unvouchered record, 5 December 2003, 17:15h, Perdizes (MG), air 26.6 o C, record file EleuthpenaxavMG1bAAGb. D—Spectrogram of the call of Ischnocnema juipoca , unvouchered topotype, 2 January 2004, 19:40h, Campinas/Joaquim Egídio (SP), air 17.0 o C. Record file EleutherojuipocaSP2AAGb.

Figures

FIGURE 1. Ischnocnema penaxavantinho sp. n.. Male AAG-UFU 4124, topotype. A—Dorsal and B—Lateral views of head. C—Palm of left hand and D—Plant of left foot.

FIGURE 2. Ischnocnema penaxavantinho sp. n.. above left: holotype (male, ZUEC 13639), Above right: a topotype (male, AAG-UFU 4124), below: a specimen from Perdizes – MG tentatively attributed to the new species (male, AAG- UFU 2616).

FIGURE 3. Two closely related species of Ischnocnema. Above Ischnocnema juipoca (Atibaia, SP). A—Female (AAG- UFU 4203), B—Male (AAG-UFU 4202). Below Ischnocnema penaxavantinho sp. n. (paratopotypes). C—Female (ZUEC 13647), D—Male (AAG-UFU 4122). All specimens are adults. Note smaller size and the darker grey coloration of I. penaxavantinho sp. n..

FIGURE 4. Two closely related Ischnocnema species in life. Above Ischnocnema penaxavantinho sp. n. (topotype) (AAG-UFU 4124). Below Ischnocnema juipoca from Poços de Caldas, MG (AAG-UFU 4132).