Kalophrynus minutus Imbun, Fui Lian, Lakim & Majuakim, 2025

Kalophrynus minutus Imbun, Fui Lian, Lakim & Majuakim sp. nov.

Materials

Type status: Holotype. Occurrence: catalogNumber: SP 26180 ; occurrenceRemarks: collected under dead leaves; recordedBy: Paul Imbun; David Sumpongol; Benedict Butit; Yusili Kumin; Martina Latim; Asmie binti Mian; sex: Male; lifeStage: adult; disposition: in collection; occurrenceID: 0E3A686C-0BEE-55E9-84B9-541CC9D11B5B; Location: continent: Borneo; country: Malaysia; stateProvince: Sabah; municipality: Keningau; locality: Zoology Trail, Crocker Range Park ; minimumElevationInMeters: 1200; maximumElevationInMeters: 1216; verbatimCoordinates: 5°27’29”N, 116°04’15”E; verbatimLatitude: 5°27’29”N; verbatimLongitude: 116°04’15”E; verbatimCoordinateSystem: degrees minutes seconds; Identification: identificationID: SP 26180; Event: eventDate: 29 Oct 2006; Record Level: institutionID: Sabah Parks; institutionCode: SP; basisOfRecord: PreservedSpecimen GoogleMaps

Type status: Paratype. Occurrence: catalogNumber: SP 20826-27 ; occurrenceID: 6E4BD4D8-0366-5479-B643-F8EF09C3EF19; Location: country: Malaysia; stateProvince: Sabah; municipality: Keningau; locality: Entomology Trail, Crocker Range Park ; verbatimElevation: 1216 m; Event: eventDate: 5/24/2005; Record Level: institutionID: Sabah Parks; institutionCode: SP; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: catalogNumber: SP 21204-05 ; occurrenceID: 3CC9E30F-620A-5C19-9E43-8DCF3A94DFEE; Location: country: Malaysia; stateProvince: Sabah; municipality: Keningau; locality: Zoology Trail, Crocker Range Park ; verbatimElevation: 1200 m; Event: eventDate: 11/9/2005; Record Level: institutionID: Sabah Parks; institutionCode: SP; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: catalogNumber: SP 21206-08 ; occurrenceID: 3BCD9032-8D96-5E45-8474-09CB9B5882E7; Location: country: Malaysia; stateProvince: Sabah; municipality: Keningau; locality: Entomology Trail, Crocker Range Park ; verbatimElevation: 1216 m; Event: eventDate: 11/14/2005; Record Level: institutionID: Sabah Parks; institutionCode: SP; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: catalogNumber: SP 21209-10 ; occurrenceID: FD777F3F-366C-58FB-9407-5870C86482E5; Location: country: Malaysia; stateProvince: Sabah; municipality: Keningau; locality: Zoology Trail, Crocker Range Park ; verbatimElevation: 1200 m; Event: eventDate: 11/15/2005; Record Level: institutionID: Sabah Parks; institutionCode: SP; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: catalogNumber: SP 21697-99 ; occurrenceID: F8FAF680-167F-5BB8-A367-523DDF003A4C; Location: country: Malaysia; stateProvince: Sabah; municipality: Keningau; locality: Zoology Trail, Crocker Range Park ; verbatimElevation: 1200 m; Event: eventDate: 4/8/2006; Record Level: institutionID: Sabah Parks; institutionCode: SP; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: catalogNumber: SP 21713 ; occurrenceID: 146D469F-6882-528F-B409-E442FB15FF70; Location: country: Malaysia; stateProvince: Sabah; municipality: Keningau; locality: Entomology Trail, Crocker Range Park ; verbatimElevation: 1216 m; Event: eventDate: 4/10/2006; Record Level: institutionID: Sabah Parks; institutionCode: SP; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: catalogNumber: SP 26074 ; occurrenceID: C72A5766-05A9-5DAF-B809-4E005F851A00; Location: country: Malaysia; stateProvince: Sabah; municipality: Keningau; locality: Zoology Trail, Crocker Range Park ; verbatimElevation: 1200 m; Event: eventDate: 9/8/2006; Record Level: institutionID: Sabah Parks; institutionCode: SP; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: catalogNumber: SP 26076 ; occurrenceID: 57D2AEBA-E943-501B-B867-39AB08E04D1A; Location: country: Malaysia; stateProvince: Sabah; municipality: Keningau; locality: Zoology Trail, Crocker Range Park ; verbatimElevation: 1200 m; Event: eventDate: 9/8/2006; Record Level: institutionID: Sabah Parks; institutionCode: SP; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: catalogNumber: SP 26097 ; occurrenceID: 7E4ABB54-B861-584A-9A8E-B0B77F9A8EA1; Location: country: Malaysia; stateProvince: Sabah; municipality: Keningau; locality: Zoology Trail, Crocker Range Park ; verbatimElevation: 1200 m; Event: eventDate: 9/11/2006; Record Level: institutionID: Sabah Parks; institutionCode: SP; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: catalogNumber: SP 26179 ; occurrenceID: FD029B6D-2E0C-5142-8FD0-EC484EB1D40E; Location: country: Malaysia; stateProvince: Sabah; municipality: Keningau; locality: Zoology Trail, Crocker Range Park ; verbatimElevation: 1200 m; Event: eventDate: 10/29/2006; Record Level: institutionID: Sabah Parks; institutionCode: SP; basisOfRecord: PreservedSpecimen

Type status: Paratype. Occurrence: catalogNumber: SP 26181-84 ; occurrenceID: 6FF9024F-AE20-589B-A3AF-B2958D4FF1AC; Location: country: Malaysia; stateProvince: Sabah; municipality: Keningau; locality: Zoology Trail, Crocker Range Park ; verbatimElevation: 1200 m; Event: eventDate: 10/29/2006; Record Level: institutionID: Sabah Parks; institutionCode: SP; basisOfRecord: PreservedSpecimen

Description

Description of holotype: A small species of Kalophrynus , adult males 18.2–20.6 mm (mean ± SE 19.52 ± 0.17, n = 15), adult females 21.1–24.2 mm (mean 22.87, n = 3). Habitus stocky; head not as wide as trunk; head slightly wider than long; snout broadly rounded or obtusely pointed, slightly projecting; nostril lateral, closer to tip of snout than to eye; canthus distinct, weakly rounded, not constricted; lores vertical, not concave; eye diameter slightly shorter than snout length; interorbital about twice width of upper eyelid; tympanum distinct, diameter slightly less than half eye diameter; palate with two crenulate ridges. Fingers and toes with narrow, rounded tips; fleshy web at bases of fingers; extension of fourth finger beyond web shorter than terminal phalanx of third finger; third finger about twice length of second finger; second finger longer than first; fourth finger with one subarticular tubercle, third finger with three; a large, round outer palmar tubercle. Fifth toe shorter than third; foot with fleshy web to tips of first two toes, third and fifth toes with one phalanx free, fourth toe with three phalanges free; toes with low, but large subarticular tubercles; a low, oval inner metatarsal tubercle and an indistinct, round outer one. Skin of dorsum smooth or with few to many low, rounded tubercles; skin of back without deep glandular layer; an oblique dorsolateral row of round, glandular tubercles from above the tympanum to the groin; a U-shaped, thickened skin with dark glandular between the tympanum and the axilla; throat smooth, abdomen weakly granular.

Measurements (mm) and body proportions ( holotype in parentheses): SVL 18.2–24.2 mm (19.6), T / SVL 0.427–0.511 (0.485), HW / SVL 0.311–0.415 (0.327).

Colour in life: Upper body tan to beige depending on lighting of environment, underside of the body lighter colour than the upper body (Fig. 2 View Figure 2 ).

Colour in preservative (Fig. 3 View Figure 3 ): Above pale tan, uniform or with scattered small black dots or with a thick X-shaped mark over the shoulders with its anterior arms forming a dark interorbital mark and the posterior arms ending just behind shoulders; the dorsolateral row of tubercles white with black edging; ventral surfaces whitish; throat usually with irregular pair of dark longitudinal bands; chest and abdomen with small irregular black markings or small black dots; ventral surfaces of limbs whitish with a few black dots; a large, round, black ocellus in the groin, larger than eye; anterior and posterior faces of thigh with or without one to four black rimmed light spots.

Secondary sexual characteristics: Males with slit-like vocal sac openings on each side of the tongue; males without dorsal spinules, nuptial pads or glands on the arm.

Diagnosis

A small species of Kalophrynus , adults < 25 mm; fourth finger with a single subarticular tubercle, free portion of fourth finger less than length of terminal phalanx of third finger; fifth toe shorter than third; a large black inguinal ocellus.

Etymology

The specific epithet is taken from the Latin adjective minutus for small, in reference to the new species having the smallest maximum body size in the genus Kalophrynus .

Distribution

Kalophrynus minutus sp. nov., a new species, is only known from two localities on the Crocker Range Park at elevations between 1,200 m a. s. l. to 1,216 m a. s. l. in lower montane tropical forest.

Ecology

A terrestrial and sub-fossorial frog species, the adult individuals can be found on dead leaves or the soft soil of the forest floor. Due to its diminutive size and leaf litter colouration, the species can be challenging to detect. Several individuals of the species have been observed in their habitat on each survey. Individuals were found away from ponds or streams or other waterbodies when sampling was done at the type locality. Eggs and tadpoles have never been observed.

Taxon discussion

Comparisons: The new species was compared with closely-related congeners of Kalophrynus in Borneo and Indo-Malesian Regions, based on morphological characters (Suppl. material 1). The comparative morphological data were obtained from literature. Three characters of Kalophrynus minutus , new species, distinguish it from most Indo-Malesian species of the genus: the small snout-vent length, the large, solid black ocellus in the groin and the single subarticular tubercle between the palmar tubercle and the tip of the fourth finger. This species resembles K. eok ( Das and Haas 2003) and K. subterrestris ( Inger 1966) in having a single subarticular tubercle under the fourth finger, but it differs from those two in having a large, black inguinal ocellus and in size. Dring (1983) said that subarticular tubercles of K. nubicola were indistinct or absent, but that species differ from K. minutus in lacking an inguinal ocellus. The remaining seven species from the Indo-Malesian region, discussed hereafter, differ from K. minutus in having two subarticular tubercles under the fourth finger. In addition, K. minutus differs from K. intermedius in size [ K. intermedius females 37–40 mm ( Inger 1966)] and in the black ocellus (absent in K. intermedius ). Kalophrinus minutus also differs from K. baluensis and K. heterochirus in lacking light spots within the inguinal ocellus and in size [females of K. baluensis 39 mm ( Kiew 1984), females of K. heterochirus 30–33 mm ( Inger 1966)]. Males of K. bunguranus , K. meizon and K. robinsoni have either spinules on the back or distinct nuptial pads or both, whereas males of K. minutus have neither ( Inger and Stuebing 2005, Zug 2015). The males of K. minutus , on which this statement is based, were caught while calling and hence are considered adult. Kalophrynus punctatus , which differs from K. minutus in having two subarticular tubercles under the fourth finger, also differs from the new species in having the fifth toe as long as or longer than the third and in lacking a dorsolateral row of black-edged white glandules. Kalophrynus minutus is the only one of these Indo-Malesian species in which most individuals have 1–4 black-edged light spots on the rear of the thigh.