Pristimantis loeslein, Castillo-Urbina & Vences & Aguilar-Puntriano & Glaw & Köhler, 2023

Castillo-Urbina, Ernesto, Vences, Miguel, Aguilar-Puntriano, Cesar, Glaw, Frank & Koehler, Joern, 2023, Contributing to the taxonomic inventory of green-colored rain frogs: A new species of the Pristimantis lacrimosus group (Anura: Strabomantidae) from the southern Cordillera Azul, central Peru, Vertebrate Zoology 73, pp. 1047-1061 : 1047

Pristimantis loeslein sp. nov.

Holotype.

MUSM 40302 (FGZC 6257), adult male, from Abra La Divisoria (9°12′01″S, 75°47′43″W, 1650 m above sea level), southern Cordillera Azul, Provincia Leoncio Prado, Departamento Huánuco, Peru, collected on 8 November 2019 by Ernesto Castillo-Urbina, Frank Glaw and Jörn Köhler.

Paratypes.

MUSM 40301 (FGZC 6256), MUSM 40303 (FGZC 6258), two adult males, same data as holotype; HLMD-RA-3239 (FGZC 6270), adult male, same data as holotype, except for being collected on 10 November 2019.

Etymology.

The species is named after the German family Löslein (from Erlangen and Munich) in recognition of supporting taxonomic research and species conservation in Peru through the BIOPAT initiative. The name is treated as a noun in apposition.

Definition.

A species assigned to the genus Pristimantis and in particular to the P. lacrimosus species group based on molecular phylogenetic relationships and overall morphological similarities. Pristimantis loeslein sp. nov. is characterized by the following combination of characters: (1) Skin on dorsum smooth; skin on flanks with small scattered low subconical tubercles; skin of venter coarsely areolate; discoidal fold present, weakly defined; dorsolateral folds absent; (2) tympanic membrane and tympanic annulus present, round, its length about 2/5 of eye diameter; its upper edge slightly concealed by inconspicuous supratympanic fold; (3) snout acuminate in dorsal view, slightly rounded to almost truncate in profile, lacking distinct rostral papilla; (4) interorbital region flat, broader than upper eyelid; upper eyelid with 1-3 distinct small subconical tubercles; cranial crests absent; (5) dentigerous processes of vomers low, widely separated, posteromedial to choanae; (6) adult males with prominent subgular vocal sac and vocal slits; adult males with inconspicuous nuptial pads on the proximal dorsal part on thumb; (7) first finger shorter than second; all fingers long, discs broadly expanded, rounded to truncate in outline, with circumferential grooves; all fingers bearing a hyperdistal tubercle; fingers with narrow, weakly defined lateral fringes; fingers without webbing; (8) few low ulnar tubercles present or absent; knee and heel tubercles absent; (9) tarsal fold not evident; tarsus bearing row of few elongated low tubercles; (10) inner metatarsal tubercle prominent, oval, approximately 4 × the size of round conical outer metatarsal tubercle; few low supernumerary plantar tubercles; (11) all toes with hyperdistal tubercles; toes with narrow lateral fringes; traces of basal webbing present between toes; discs expanded, rounded to truncate in outline, slightly smaller than those on fingers, bearing circumferential grooves; toe V distinctly longer than toe III; (12) in life, predominantly yellowish green to olive-green dorsal coloration, with darker markings; throat, chest and venter yellow; iris copper to bronze with black reticulation; (13) SVL of adult males 20.5-23.3 mm (n = 4); (14) advertisement call consisting of a single tonal note with 98-110 ms duration, repeated in long call series.

Diagnosis.

Pristimantis loeslein is most closely related to the nominal species P. aureolineatus , P. lacrimosus , P. pluvialis , P. pulchridormientes , and P. zorro (see Fig. 1 ). From these, the new species (characters in parentheses) differs as follows: P. aureolineatus mainly differs by dorsal skin texture finely shagreened (vs. smooth), snout protruding in lateral profile (vs. slightly rounded to almost truncate), and a creamy-yellow interorbital bar, extending to upper eyelids and posteriorly to the sacrum (vs. interorbital bar blackish without extension); P. pulchridormientes mainly differs by absence of tubercles on upper eyelid (vs. 1-3 small subconical tubercles), dentigerous processes of vomers absent (vs. present, low), inner metatarsal tubercle 2 × the size of outer metatarsal tubercle (vs. 4 ×), dorsum yellowish brown in life (vs. yellowish green to olive-green), posterior surfaces of thighs and shanks bright red (vs. brownish to pinkish grey), and note duration of 31-75 ms in advertisement calls (vs. 98-110 ms); P. pluvialis mainly differs by skin on flanks smooth (vs. with small scattered subconical tubercles), snout rounded in profile (vs. slightly rounded to almost truncate), presence of a small rostral tubercle (vs. absence), inner metatarsal tubercle 2.5 × the size of outer metatarsal tubercle (vs. 4 ×), white venter in life (vs. yellow), dorsum orange-brown in life (vs. yellowish green to olive-green), and 23-58 ms note duration in advertisement calls (vs. 98-110 ms); P. lacrimosus mainly differs by the presence of a rostral papilla (vs. absence), discoidal fold absent (vs. present, weakly defined), inner metatarsal tubercle 5-6 × the size of outer metatarsal tubercle (vs. 4 ×), yellow, golden-brown, or reddish-brown dorsal coloration in life (vs. yellowish green to olive-green); P. zorro mainly differs by the absence of a discoidal fold (vs. present, weakly defined), presence of small rostral papilla (vs. absence), absence of tubercles on upper eyelid (vs. 1-3 small subconical tubercles), cream venter in life (vs. yellow), and presence of dark blotch covering the front of the face, including inter-nostril area forming a facial mask (vs. absence). Furthermore, P. loeslein differs from all nominal species in the P. lacrimosus group with respective genetic data available by substantial genetic divergence in the 16S rRNA gene (uncorrected p-distances> 7.9%).

Species without analyzed 16S rRNA sequence data allocated to the P. lacrimosus group (sensu Carrión-Olmedo and Ron 2021) are: P. deyi , P. latericius , P. mendax , P. olivaceus (see Discussion), P. padiali , P. pardalinus , P. pseudoacuminatus , P. royi , P. tantanti , P. waoranii , and P. zimmermanae . From these, P. loeslein differs as follows: P. deyi mainly differs by dorsolateral folds present (vs. absent), rostral papillae present as a fleshy process (vs. absent), snout protruding and inclined posteroventrally in profile (vs. slightly rounded to almost truncate), and predominantly brownish dorsal color in life (vs. yellowish green to olive-green); P. latericius mainly differs by dorsal skin finely granular (vs. smooth), inner metatarsal tubercle 2 × the size of outer metatarsal tubercle (vs. 4 ×), and dorsal color in life red to light orange (vs. yellowish green to olive-green); P. mendax (sensu Morales and Icochea 2000) mainly differs by snout round in dorsal view (vs. acuminate), dorsal skin shagreened bearing conical tubercles (vs. smooth, lacking tubercles), discoidal fold absent (vs. present, weakly defined), dentigerous processes of vomers absent (vs. present, low), tarsal fold evident, sigmoid (vs. not evident), and heel tubercles conspicuous (vs. absent); P. olivaceus mainly differs by the presence of a rostral papilla (vs. absence), dorsal skin texture shagreened with scattered tubercles (vs. smooth, lacking tubercles), snout protruding in profile (vs. slightly rounded to almost truncate), and discoidal fold distinct (vs. weakly defined); P. padiali mainly differs by ventral skin weakly areolate (vs. coarsely areolate), snout protruding and inclined posteroventrally in profile (vs. slightly rounded to almost truncate), inner metatarsal tubercle 2 × the size of outer metatarsal tubercle (vs. 4 ×), eyelid tubercles absent (vs. 1-3 small subconical tubercles), subgular vocal sacs and vocal slits absent (vs. present), and heel tubercles present (vs. absent); P. pardalinus mainly differs by lateral fringes on fingers broad (vs. weakly defined), heel bearing small tubercles and one prominent tubercle (vs. absent), and white venter in life (vs. yellow); P. pseudoacuminatus mainly differs by snout acutely rounded in profile (vs. slightly rounded to almost truncate), discoidal fold absent (vs. present, weakly defined), inner metatarsal tubercle 5 × the size of outer metatarsal tubercle (vs. 4 ×), tarsus lacking tubercles (vs. bearing a row of few elongated low tubercles), and white venter in life (vs. yellow); P. royi differs by snout bluntly rounded in dorsal view (vs. acuminate), nostrils directed dorsolaterally (vs. laterally), supernumerary palmar and plantar tubercles absent (vs. presence of round supernumerary palmar tubercles and few low plantar tubercles), and an advertisement call with note durations of 24-26 ms ( Morales 2007) (vs. 98-110 ms); P. tantanti mainly differs by absence of a tympanic membrane and annulus (vs. presence), absence of a discoidal fold (vs. presence, weakly defined), and prominent ulnar and tarsal folds (vs. absent, not evident); P. waoranii mainly differs by absence of tubercles on upper eyelid (vs. 1-3 small subconical tubercles), presence of a tarsal fold (vs. absence), venter translucent white to creamy white in life (vs. yellow), and bright golden-brown dorsal color of males in life (vs. yellowish green to olive-green); P. zimmermanae mainly differs by snout acute in profile (vs. slightly rounded to almost truncate), dentigerous processes of vomers absent (vs. present, low), and a pulsatile advertisement call (vs. tonal).

Although currently not associated with the P. lacrimosus species group, P. rhodostichus shares several characters with other species in the group (see Duellman and Lehr 2009; Chávez and Catenazzi 2016; Shepack et al. 2016) and should possibly considered a member of it. Pristimantis rhodostichus mainly differs from the new species by a prominent discoidal fold (vs. weakly defined), dorsum shagreened with numerous scattered conical tubercles (vs. smooth, lacking conical tubercles), snout acutely rounded above and inclined posterolaterally in profile (vs. slightly rounded to almost truncate), and a cream venter in life (vs. yellow).

Description of the holotype.

Adult male (SVL 21.0 mm) in good state of preservation (Fig. 2 ). Body slender; head slightly longer than wide, wider than body; snout acuminate in dorsal view, slightly rounded, almost truncate in lateral profile, rostral papilla absent; canthus rostralis distinct, straight in dorsal view, slightly rounded in cross-section; loreal region concave; interorbital region flat, no cranial crests; eye large, protuberant; upper eyelid width about 62% of interorbital distance; right eyelid bearing one subconical tubercle, left eyelid bearing two subconical tubercles. Tympanic membrane and annulus distinct, rounded, with inconspicuous supratympanic fold, slightly obscuring anterodorsal annulus; horizontal diameter of tympanum about 14% of head length, separated from eye by a distance about two thirds of tympanum length; choanae large, rounded, not concealed by palatal shelf of maxillary arc; dentigerous processes of vomers low, posteriomedian to choanae, separated by a distance of about twice their length, each bearing a transverse row of four to five teeth; tongue removed as tissue sample. Skin on dorsum smooth; dorsolateral folds absent; skin on flanks with few minute scattered subconical tubercles; skin on belly coarsely areolate; skin on throat and chest smooth; discoidal fold present, but very weakly defined; skin in upper cloacal region smooth, with few minute rounded tubercles. Forearms slender, each bearing a row of three rounded tubercles at ventral side of lower arm; fingers long and slender, all with expanded discs, those on fingers I and II rounded, those on fingers III and IV truncate in outline; finger discs with circumferential grooves; fingers bearing narrow lateral fringes, basal webbing between fingers absent; relative lengths of fingers I <II <IV <III; three subarticular tubercles on finger III, all tubercles well defined, round in ventral and lateral view; several round supernumerary tubercles present, prominent at the base of the fingers and lower at the palmar surface; palmar tubercle bifid, heart-shaped, about the same length and 130% width of ovoid thenar tubercle; inconspicuous nuptial pad on proximal dorsal part of thumb. Hindlimbs slender; tibia length about 51% of SVL; skin on upper surfaces of hindlimbs smooth, with scattered barely recognizable low rounded tubercles; foot length about 45% of SVL; posterior surfaces of thighs smooth, ventral surfaces of thighs weakly areolate; knee and heel lacking tubercles; no distinct tarsal fold; tarsus bearing a row of three elongated tubercles at median level; toes bearing narrow lateral fringes; trace of basal webbing between all toes; discs on toes expanded, very slightly smaller than those on fingers, rounded in outline, bearing circumferential grooves; relative lengths of toes I <II <III <V <IV; toe V distinctly longer than toe III, disc on toe V reaches proximal edge of hyperdistal tubercle on toe IV, disc on toe III reaches distal edge of penultimate subarticular tubercle on toe IV; subarticular tubercles rounded, prominent; plantar surface with few low supernumerary tubercles; inner metatarsal tubercle prominent, elliptical, approximately four times the size of rounded and conical outer metatarsal tubercle. For morphological measurements see Table 1 .

In life (Fig. 3 ), dorsal surfaces yellowish green, olive--green to greenish brown. Blackish brown interorbital stripe; anterior head yellowish green with some reddish brown marbling; scapular region with some faint irregular dark flecking; dorsum with two interrupted curved black lines at the border to flanks; flanks bright green with some irregular orange-brown flecking; loreal region dark green to brown, with dark brown canthal stripe; supratympanic fold and region posterior to tympanum dark brown; upper surfaces of limbs dark green to brown with scattered darker blotches and flecks; belly bright yellow; throat and chest transparent yellow with some fine brown spotting; ventral surfaces of limbs brownish to pinkish grey; ventral surfaces of finger and toe discs yellowish green; bones white; iris bronze, with faint horizontal copper streak, irregular black reticulation.

After two years in preservative (Fig. 2 ), ground color greyish brown to cream, with a brown middorsal area, bordered by fine interrupted black lines; faint pinkish brown fleck in sacral region; black interorbital stripe; flanks greyish cream with some irregular reddish brown markings; dorsal surfaces of limbs greyish brown with dark brown markings; belly, throat and chest greyish cream; ventral surfaces of thighs yellowish cream.

Variation.

For variation in measurements among the four males of the type series, see Table 1 . Some variation is evident with respect to the dorsal color pattern. Compared to the holotype, paratype MUSM 40301 has a less contrasting dorsal color pattern, lacking dark brown or blackish lines and spots on dorsum, and has a barely recognizable dark interorbital bar. The transverse dark bars on hindlimbs are also very indistinct. Some irregular reddish-brown flecking was evident in life dorsally in the sacral region (Fig. 4a ). The paratype MUSM 40303 exhibits a more contrasting dorsal pattern compared to the holotype. Dark interrupted lines on dorsum appeared more blackish in life and additional black flecking is present on the flanks, whereas transverse dark bars on hindlimbs are only evident in the anterior parts (Fig. 4c ). The paratype HLMD-RA-3239 is very similar in dorsal color pattern when compared to the holotype, except for a more regularly shaped dark hourglass-pattern on middorsum. Ventral coloration is virtually the same in all four specimens.

Natural history.

The type locality is an area of evergreen montane rainforest of moderate height, growing on moderate to steeply sloped terrain (Fig. 5 ). The area has partly been altered by different kinds of plantations (see also Köhler et al. 2022). Individuals were observed at night during light rainfall while calling from bushes and low shrub vegetation (secondary growth) at the side slope of a narrow dirt road. The species occurs in syntopy with Pristimantis nebulosus , P. sp. (aff. Pristimantis divnae ), Rhinella sp. ( Rhinella margaritifera group), Boana lanciformis , Dendropsophus aperomeus , Scinax cf. garbei , S. sp. (aff. Scinax ruber ), and Adenomera sp. (see also Köhler et al. 2022).

Vocalisation.

Calls were recorded on 8 November 2019, around 20:00 h, at the type locality, Abra la Divisoria, southern Cordillera Azul, 1650 m a.s.l., Departamento Huánuco, Peru (air temperature estimated by subjective feel app. 18°C). The recorded individuals could not be observed calling, but searching at the spot of sound emission revealed individuals of P. loeslein , and other individuals of P. loeslein were seen emitting the same call, leaving little doubt that recorded calls actually correspond to this species. The advertisement call consists of a single tonal note of short duration, repeated in long call series at rather long and irregular inter-call intervals (Fig. 6 ). Call series apparently can continue for several hours. Each call (= note) shows some amplitude modulation with maximum call energy being present at the beginning of the call, then rapidly dropping to about half the maximum call energy and continuously decreasing towards the call’s end. In some calls, some further subtle amplitude modulation is recognizable (Fig. 6 ), but clearly it does not qualify for the classification as pulses or pulsatile structures (see Köhler et al. 2017). Frequency is distributed in a very narrow band, harmonic frequencies and frequency modulation are absent. Numerical parameters of 85 analyzed calls, originating at leas`t from four different individuals, are as follows: call duration (= note duration) 98-110 ms (104.2 ± 3.6 ms); inter-call interval 786-3062 ms (1782.3 ± 524.0 ms); dominant frequency 2744-3021 Hz (2840 ± 109 Hz); prevalent bandwidth 2500-3300 Hz.

Distribution.

Known so far only from the type locality in the southern Cordillera Azul (Fig. 7 ). However, the species is likely to occur in other areas of montane rainforests in central Peru. Possibly, some records formerly referred to other nominal species in the P. lacrimosus group from that area (e.g., P. cf. mendax , P. lacrimosus ) may actually refer to this new species.

Figures

Figure 1. Maximum Likelihood phylogenetic tree of selected samples of Pristimantis, representing the P. lacrimosus species group and related taxa, inferred from an alignment of 1637 nucleotides of the mitochondrial 16 S rRNA gene. Three samples of Yunganastes were used to root the tree (not shown for better graphical presentation). Numbers at nodes are bootstrap values in percent (2000 pseudoreplicates; not shown if <50 %), followed by SH-aLRT values (1000 replicates; not shown if <50) as calculated with IQ-TREE. The taxon name is followed by the GenBank accession number, or voucher number for newly produced sequences (bold terminals), and the sample locality. Inset photo depicts the holotype of P. loeslein sp. nov. (MUSM 40302) in life (mirrored).

Figure 2. Preserved male holotype of Pristimantis loeslein sp. nov. (MUSM 40302, FGZC 6257) from Abra La Divisoria, Cordillera Azul, Departamento Huanuco, Peru, 1650 m a. s. l. (a) Dorsal view, (b) ventral view, (c) palmar surface of right hand, and (d) head in lateral profile.

Figure 3. Living male holotype of Pristimantis loeslein sp. nov. (MUSM 40302, FGZC 6257) from Abra La Divisoria, Cordillera Azul, Departamento Huanuco, Peru, 1650 m a. s. l., in (a) dorsolateral, (b) frontal, and (c) ventral views (SVL 21.0 mm).

Figure 4. Topotypic male paratypes of Pristimantis loeslein sp. nov. in life: MUSM 40301 (FGZC 6256) in (a) dorsolateral and (b) ventral views (SVL 20.5 mm); MUSM 40303 (FGZC 6258) in (c) dorsolateral and (d) ventral views (SVL 22.3 mm).

Figure 5. View of the forest at the type locality of Pristimantis loeslein sp. nov. at Abra La Divisoria, southern Cordillera Azul, Departamento Huanuco, Peru, at 1650 m a. s. l.; photo taken on 8 November 2019.

Figure 6. Audiospectrogram and corresponding oscillogram at 4000 ms time scale showing three advertisement calls of Pristimantis loeslein sp. nov. recorded on 8 November 2019 at Abra La Divisoria, 1650 m a. s. l., Departamento Huanuco, Peru. Below an oscillogram showing one single call (the center call from oscillogram above) at 400 ms time scale. Recording band-pass filtered at 1500 - 6000 Hz.

Figure 7. Map of central Peru with adjacent regions in northern and southern Peru, showing the known distribution of seven nominal and two candidate species of the Pristimantis lacrimosus species group as discussed in the text. In most cases, symbols refer to the respective type localities. Black lines within Peru do refer to the political borders of respective departments.