Atelopus gigas Coloma, Duellman, C, Ron, Terán-Valdez & Guayasamin, 2010, sp. nov.
Creators: name: Coloma, Luis A.
name: Duellman, William E.
name: C, Ana Almendáriz
name: Ron, Santiago R.
name: Terán-Valdez, Andrea
name: Guayasamin, Juan M.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Amphibia
Anura
Bufonidae
Atelopus
Atelopus gigas

description: Atelopus gigas sp. nov.
Holotype. KU 140320, adult female, from La Victoria, Departamento Nariño, Colombia, obtained in May 1970 by Kjell von Schneidern. According to John D. Lynch (in litt.) this locality is in Municipio de Ipiales, 38 km (by road) SE of Ipiales (0˚40' N, 77˚32' W; ~ 2700 m).
Paratypes. KU 140315 –17, 140318 (cleared-and-stained adult female), 140319, 140321 –29. Same data as holotype.
Diagnosis. (1) A large species with SVL in adult males 43.0–48.6 (mean = 45.6 mm, SD = 1.8082, n = 6), and in adult females 43.3–57.2 (mean = 53.8 mm, SD = 4.3232, n = 9); (2) hind limbs short, tibia length/SVL 0.346–0.413 (n = 15); (3) phalangeal formula of hand 2-2-3-3, basal webbing absent; (4) foot webbing formula I (0–½)-—(½–1) II (½–1+)—(1½–2+) III (½–1+)—(2–3) IV (1½–3)—(½–1½) V; (5) snout rounded to acuminate in dorsal view, slightly protruding beyond lower jaw; (6) tympanic membrane, tympanic annulus, and stapes absent; (7) dorsal surfaces of body usually smooth, bearing few warts mostly in males; (8) warts present on forearm, flanks and dorsal surfaces of thighs and shanks; spiculae present on flanks of females; (9) vertebral neural processes inconspicuous; (10) dorsum yellowish cream to yellowish tan in preservative; (11) minute gray stippling absent on dorsum of body; (12) venter cream in preservative; (13) gular region without warts, spiculae or coni.
In having a plain yellowish cream to yellowish tan dorsum in preservative, Atelopus gigas sp. nov. is most similar to A. guanujo, A. bomolochos (populations from Cutchil, Provincia Azuay, Ecuador), A. onorei Coloma, Lötters, Duellman, and Miranda-Leiva, A. ardila sp. nov. (some individuals), A. carbonerensis Rivero, A. chrysocorallus La Marca, and A. sorianoi from the Andes of Venezuela. Atelopus gigas (mean SVL of females 53.8; mean SVL of males 45.6) is significantly larger than A. guanujo (mean SVL of females 39.6; mean SVL of males 33.9). It differs from A. bomolochos and A. onorei in having coni and larger spiculae, and from A. bomolochos by lacking minute gray stippling (present in A. bomolochos). Atelopus gigas differs from A. ardila in females lacking a patch of spiculae and coni on the gular and pectoral regions (present in A. ardila), in having a nearly smooth dorsum (body smooth, bearing spiculae and coni mostly on sacral region in A. ardila), and by being significantly larger than A. ardila (mean SVL of females 46.7; mean SVL of males 38.6) (SVL of females Student’s t -test, t = 6.090, df = 45, P <0.0001; SVL of males Student’s t -test, t = 10.932, df = 67, P <0.0001). Atelopus gigas differs from A. carbonerensis and A. sorianoi in having a less protuberant snout and lacking a prominent postocular crest (postocular crest present in A. carbonerensis and A. sorianoi). Furthermore, it differs from A. carbonerensis and A. chrysocorallus by having vocal slits in males (absent in A. carbonerensis and A. chrysocorallus) and lacking a row of warts on the dorsolateral surfaces of the body in males (present in A. carbonerensis and A. chrysocorallus).
Description of holotype. (Figs. 6 A–C). Head slightly longer than wide, HLSQ and HDWD less than one third SVL (HLSQ/SVL = 0.277, HDWD/SVL = 0.266); snout rounded in dorsal view; in lateral view, profile of tip of snout to the anterior margin of jaw nearly straight and slightly protuberant; swollen gland on tip of snout absent; nostrils slightly protuberant, directed laterally, situated at level slightly posterior to apex of lower jaw; canthus rostralis distinct, nearly straight from eye to nostril; loreal region concave; lips not flared; interorbital region and occiput flat, smooth; eyelid flared without distinct tubercles; postorbital crest slightly raised, glandular; pretympanic and tympanic areas free of warts; tympanic membrane and tympanic annulus absent; postmandibular and temporal area with warts; choanae small, rounded, widely separated; tongue twice as long as wide, broadest at anterior half, free along its posterior half.
Forearm relatively short (RDUL/SVL = 0.300); palmar tubercle round, poorly defined; supernumerary palmar tubercles distinct; thenar and subarticular tubercles low raised; digital tips with round pads; thumb relatively long (THBL/HAND = 0.779), apparently having two phalanges; webbing on hands absent, fingers having lateral keels that are more conspicuous on Finger IV; relative length of fingers II<III<V<IV. Tibia relatively short (TIBL/SVL = 0.374); fold on distal half of inner edge of tarsus absent; inner metatarsal tubercle oval and flat; outer metatarsal tubercle round, slightly raised, about two thirds length of inner metatarsal tubercle; supernumerary plantar tubercles absent; subarticular tubercles flat, barely conspicuous; digital pads distinct; webbing formula of foot I(0+)—(½) II(½)—(1+) III(1)—(2+) IV(2 +)—(1) V; relative length of toes I<II<III=V<IV.
Dorsal surfaces smooth with scattered flat warts in posterolateral sacral region and on dorsal and posterior surfaces of thighs, increasing in number toward the flanks; warts on flanks and anterior and proximal upper anterior surfaces of forelimbs bear spiculae; each wart may lack or bear a single or a group (up to four) of spiculae; throat, chest, belly, undersides of limbs smooth; underside of arm rugose; cloaca opens as an inconspicuous tube at upper level of thighs, directed posteriorly; rugose margin of cloacal opening.
Color in preservative (70–75 % ethanol): dorsal surfaces of head and body pale yellowish cream, becoming pale yellowish tan posteriorly on body, flanks, and dorsal surfaces of limbs; margin of cloacal opening dark brown; minute gray stippling absent on dorsum of body (viewed at 8x magnification); warts and spiculae cream; dorsal surfaces of fingers vary from yellowish cream of inner finger and toe to yellowish tan towards outer fingers and toes; they bear a brown lines present at articular regions of phalanges, with the distal line being better defined than the rest; throat, chest, belly, and ventral surfaces of limbs uniform cream; outer metatarsal tubercle slightly lighter than adjacent areas; proximal end of tongue lacking black pigmentation, but lower lip bearing a poorly pigmented brown margin at distal end.
Measurements of holotype (mm). SVL 55.9, TIBL 20.9, FOOT 21.1, HLSQ 15.5, HDWD 14.9, ITNR 5.3, EYDM 5.8, EYNO 3.9, RDUL 16.8, HAND 13.6, THBL 10.6, SW 16.5.
Variation. Meristic variation is shown in Table 3. The paratypes resemble the holotype with the following noteworthy exceptions. There is variation in size, abundance and distribution of warts and spiculae. For example, a female (KU 140316) has more abundant warts and larger spiculae along dorsum and flanks than other females, whereas female KU 140317 has fewer warts and spiculae. Another female (KU 140317) has a more rugose plantar surface than other females. A juvenile female (KU 140321, SVL = 43.3) has more warts and spiculae than other specimens. A female (KU 140317) has a shorter than normal and deformed Finger IV. Six males differ among them in that KU 140319, and 140324 possess more abundant warts on dorsum of sacral region, thighs and shanks.
Atelopus gigas
La Victoria
Sexual dimorphism is evident in that females are larger than males (Table 3). Males have vocal slits and keratinized nuptial pads on the dorsal and inner surfaces of the thumb and of Finger III, in which they are more abundant at the proximal phalanx. The forelimbs are relatively long and slender only in females, but they are short with a stout muscular area in males (Table 3); there are significant differences in RDUL between males and females (RDUL Student’s t -test, t = 4.4105, df = 13, P <0.0007). Males lack coni and nearly lack spiculae, whereas females have coni and spiculae.
All paratypes lack a brown area surrounding cloacal opening. In preservative, the dorsal coloration varies from uniform yellowish cream (KU 140321) to dark brown (KU 140319). One individual (KU 140318) has two dark brown bars across mid-dorsum of the body and a few, small diffuse dark brown marks on the dorsal surfaces of the hindlimbs. In one female (KU 140317), the lower lip is more pigmented with brown.
Color in life: Unknown. Presumably yellow or orange by comparison with coloration in ethanol of other preserved Atelopus.
Tadpoles. Tadpoles of this species are unknown.
Distribution, natural history, and conservation status. Atelopus gigas is known only from the type locality (Fig. 5). This locality currently has cultivated areas. At La Victoria, annual mean rainfall is 1190 mm and the annual mean temperature is 13.3 ºC (Hijmans et al. 2005). At time of collection, in May 1970, four out of seven adult females were gravid. One of them (KU 140318) contained 626 ovarian eggs of about 2.15 mm of diameter (n = 15, SD = 0.151). The stomach of KU 140318 contained remains of 63 arthropods [22 Coleoptera (1 Brenthidae, 7 Carabidae, 3 Curculionidae, 4 Staphylinidae, 7 undetermined), 13 Acari, 7 Hymenoptera, 4 Diptera, 1 Aracnida, 1 Blatodea, 1 Hemiptera, 1 Homoptera, 7 undetermined insects, 5 insect larvae], vegetal material, unidentified helminth endoparasites, and some undetermined material. The largest prey was an insect larva 7.1 mm long.
Atelopus gigas is considered as Data Deficient under IUCN Red List categories and criteria, because no collecting efforts have been carried out at its only known locality. Nonetheless, a similar fate of either severe decline or extinction (as most highland species of Atelopus) is a reasonable presumption. The chytrid fungus has been reported in very close proximity to the type locality in an Ecuadorian locality at Carchi Province (Ron and Merino 2000).The risk factor of potential threat caused by the chytrid for anuran amphibian species calculated by Rödder et al. (2009: Fig. 2 C) is high at the area of its distribution.
Etymology. Gigas is a noun in apposition from the Greek word “ gigas ” that means giant. It is used in reference to the large size of this species, which is exceeded in size only by Atelopus boulengeri.
description: Published as part of Coloma, Luis A., Duellman, William E., C, Ana Almendáriz, Ron, Santiago R., Terán-Valdez, Andrea & Guayasamin, Juan M., 2010, Five new (extinct?) species of Atelopus (Anura: Bufonidae) from Andean Colombia, Ecuador, and Peru, pp. 1-54 in Zootaxa 2574 on pages 12-16, DOI: 10.5281/zenodo.197448