12Recent reviews on sexual dichromatism in frogs included Mannophryne trinitatis as the only example 13 they could find of dynamic dichromatism (males turn black when calling) within the family 14 Aromobatidae and found no example of ontogenetic dichromatism in this group. We demonstrate 15 ontogenetic dichromatism in M. trinitatis by rearing post-metamorphic froglets to near maturity: the 16 throats of all individuals started as grey coloured; at around seven weeks, the throat became pale 17 yellow in some, and more strongly yellow as development proceeded; the throats of adults are grey 18 in males and variably bright yellow in females, backed by a dark collar. We demonstrated the degree 19 of throat colour variability by analysing a large sample of females. The red: green (R:G) ratio ranged 20 from ~1.1 to 1.4, reflecting variation from yellow to yellow/orange, and there was also variation in 21 the tone and width of the dark collar, and in the extent to which the yellow colouration occurred 22 posterior to the collar. Female M. trinitatis are known to be territorial in behaviour. We show a quality. Our field observations on Tobago's M. olmonae showed variability in female throat colour 25 and confirmed that males in this species also turn black when calling. Our literature review of the 20 26 Mannophryne species so far named showed that all females have yellow throats with dark collars, 27 and that male colour change to black when calling has been reported in eight species; in the 28 remaining 12 species, descriptions of males calling are usually lacking so far. We predict that both 29 dynamic and ontogenetic sexual dichromatism are universal in this genus and provide discussion of 30 the ecological role of dichromatism in this genus of predominantly diurnal, non-toxic frogs, with 31 strong paternal care of offspring. 32 Keywords: Aromobatidae, Anurans, Mannophryne, sexual dichromatism, sexual signalling 33 36 found, a wide diversity of visual signalling (movements, colours, patterns, shapes) both in diurnal 37 and in nocturnal species is becoming established. For example, Rojas (1) reviewed the roles of 38 colours and patterns, Hodl and Amezquita (2) reviewed and classified the variety of visual signals, 39 and Starnberger et al. (3) discussed the multimodal roles of the vocal sac in signalling: not only 40 auditory, but also visual and chemical in some cases. One category of visual signals involves sexual 41 dichromatism, reviewed by Bell and Zamudio (4). They distinguished two types. First, dynamic 42 dichromatism, restricted to males, where the male develops a temporary colour signal related to 43 courtship and breeding. The review identified 31 species in nine families where this occurred. 44 Second, ontogenetic dichromatism, where either males or females develop a permanent colour 45 difference as they mature. The review found this reported from 92 species in 18 families. Bell et al. 46 (5) extended the dataset for dynamic dichromatism to 178 species in 15 families and subfamilies. Dynamic sexual dichro...
