Mannophryne spp.

Prof. Enrique La Marca
Universidad de Los Andes, Venezuela
Last update: 02 June, 2004

Mannophryne is a genus of one of the largest anuran families in the Neotropics, the Dendrobatidae. It is distinguished from other Dendrobatids by the presence of a dark transverse 'collar' on the lower throat and upper chest. They also have elaborate behavioural patterns that include pulsation of a yellow throat (an aggressive display used by females to defend territories), and toe tip jumping (a visual display employed by males for courtship of females). Females of MM. collaris, herminae and trinitatis are more aggressive than males, an unusual condition among Dendrobatids and most probably related to parental care, since transport of larvae on the back of a parent is performed almost exclusively by males. Males do not use tactile (that is, close-range) stimuli to lead females to ovipositing sites, using instead elaborate vocal and visual displays at long distance. The collar is most probably used by females in association with the visual displays of their yellow throats. Its function, thus, is that of intraspecific communication with territorial purposes. The collar is usually not exhibited by adult males, but it is present in both male and female juveniles of all species.

Males usually reach a maximum size of between 21 and 25mm, and females between 22 and 30mm. MM. oblitterata and riveroi are exceptions in that males reach between 33 and 35mm and females between 36 and 46mm. The largest sizes are those of M. riveroi, being thus the second largest Dendrobatid, after Aromobates nocturnus. Coloration of female specimens consists usually of a brown or grey-brown back, occasionally with a light inguinal stripe; throat is usually completely yellow, collar dark brown; belly white or pale yellow; dorsal surfaces of legs distinctly barred black on bronze. Iris has been indicated to vary between reddish copper, light bronze, gold to silvery gold, and may possess or not reticulation. Males are duskier than females and less yellowish on ventral surfaces. Mature males usually have a blackened dorsum; throat and chest blackened, paler than belly, and a dark grey belly.

Characters useful to diagnose species of Mannophryne are chest markings, throat pattern of melanophores, and web development. MM. olmonae and neblina have a narrow collar, uniformly coloured; MM. trinitatis and riveroi have a wide collar without conspicuous markings. MM. collaris, cordilleriana, herminae and oblitterata possess a wide collar with pale flecks or spots and M. yustizi has a wide collar with large pale dots. Throat pattern of coloration is useful to distinguish two groups within the genus: MM. collaris, cordilleriana, herminae, oblitterata and yustizi have reduced distribution of bright coloration on throat, and also have melanophores on anterior part of throat extensively distributed, while the remaining species have extensive bright coloration on throat and lack melanophores on lips (or, when present, the latter are restricted just to the borders of lips). Mannophryne neblina is unique in having larvae with large labial papillae, a condition not seen in other Mannophryne tadpoles, although present is some other Dendrobatids. M. neblina is also the only collared frog with uniformly coloured back (all others are spotted) and brassy gold band covering upper lips. M. riveroi is unique within the genus in possessing a posterioventral transversal dark band. Extensive foot webs are exhibited by MM. collaris, cordilleriana, oblitterata and riveroi; all others have reduced foot webs.

Vocalisation is known for a few species. M. collaris has a rapid series of chirps lasting between 10 and 20 seconds. M. herminae has a call consisting of paired notes repeated at a rate of about 10 notes per second, with a dominant frequency of about 4500Hz. M. olmonae has a call containing from 36 to 347 single notes, repeated at a rate of three notes per second with a frequency of each note increasing from about 4800 to 5700Hz. A second kind of call, called the 'harsh call', has four harmonics per note, located between the frequencies of 2100 to 4200Hz. M. riveroi has a series of shrill notes repeated at a rate of about three to four notes per second with a dominant range of between 2250 and 3400Hz, with three other harmonics at about 1500, 4600 and 5800Hz. M. trinitatis has an advertisement call consisting of a series of paired notes uttered at a rate of about 10 notes per second. When courting a female, the male switches to a trilled call with notes emitted at a rate of about 15 notes per second. The dominant frequency range for this kind of call is located between approximately 4000 and 4900Hz.

Members in the genus inhabit humid forests with a mean annual precipitation of 1100 to 2200mm, and mean annual temperatures of 18 to 24°C, parameters that may constitute useful predictors of the occurrence of these frogs in the northern mountains of South America. In a few instances, places inhabited by Mannophryne frogs are shared with species of the genus Nephelobates. The latter are slender frogs without collars, having a cloacal sheath, and large teeth and more reduced nasal bones than species of Mannophryne. Almost nothing is known about natural prey items of Mannophryne; unpublished data indicate that some Mannophryne species feed on beetles, large ants and mites.

Mannophryne species live exclusively in Venezuela and the island of Trinidad and Tobago. Most of the geographical range is dominated by mountains, although M. olmonae reaches down to sea level. Thus, M. collaris inhabits the Cordillera de Marida; M. cordilleriana the Sierra de Santo Domingo; MM. herminae, neblina and oblitterata occur in the Cordillera de La Costa; M. olmonae at altitudes of 5 to 100m in the island of Tobago; M. riveroi lives in the Serrania de Paria; M. trinitatis in the Northern Range of the island of Trinidad, and adjacent Venezuela; M. yustizi in the Sierra de Portuguesa. Cases of simpatry are documented for MM. herminae and neblina at Rancho Grande, MM. oblitterata and trinitatis in Guatopo National Park, and MM. riveroi and trinitatis in Cerro Azul, Peninsula de Paria; all of them in the Venezuelan Caribbean coastal system. These cases could represent speciation in situ or dispersal events, since most distributions are allopatric.