Part 15

Some of the most distinctive characters of the species of Smilisca are color and pattern of the living frogs. Although many chromatic features are lost or subdued in preserved specimens, the patterns usually persist.

Metachrosis

Change in color, well known in frogs, is common in hylids, especially in species having green dorsal surfaces (Phyllomedusa is a notable exception). The non-green Smilisca (puma, sila, and sordida) changes color, but this mostly is a change in intensity of color. In these species the markings usually are most distinct at night; frequently by day the frogs become pallid. The most striking examples of metachrosis in Smilisca are found in the baudini group, in which the dorsal ground-color changes from green to tan; correlated with the change in ground-color may be a corresponding change in the dorsal markings, but the dorsal markings may change to the opposite color.

Chromosomes

Chromosomes of all six species of Smilisca were studied by means of the propriono-orcein squash technique described by Duellman and Cole (1965). Karyotype analysis was attempted for several species by means of intraperitoneal injections of colchicine, which affected the mitotic cells as desired, but the testes examined contained too few mitotic cells to allow accurate determination of karyotypes.

Haploid (n) chromosome numbers were determined from cells in diakinesis, metaphase I, and metaphase II of meiosis. Diploid (2n) chromosome numbers were determined from cells in late prophase and metaphase of mitosis. Chromosome counts from as few as 23 meiotic cells of S. phaeota and as many as 80 cells of S. sordida reveal a constant haploid (n) number of 12; counts of chromosomes in one to five mitotic cells in all species, except S. sila, reveal that the diploid (2n) number is 24.

NATURAL HISTORY

Breeding

Like most hylid frogs Smilisca is most readily collected and observed when individuals congregate for breeding.

Time of Breeding

Smilisca breeds primarily in quiet water and reaches its height of breeding activity at times of plentiful rainfall,--usually from May through October. Through most of its range Smilisca baudini breeds in those months, but in some places where abundant rain falls in other seasons, the species breeds at those times. For example, in southern El Peten and northern Alta Verapaz, Guatemala, Smilisca baudini has been found breeding in February and March. The other pond-breeding species (S. cyanosticta, phaeota, and puma) live in regions lacking a prolonged dry season, and possibly they breed throughout the year, but breeding activity seems to be greatest in the rainiest months.

The two stream-breeding species (S. sila and sordida) breed in the dry season when the streams are low and clear, principally in December through April. At high elevations the species sometimes breed in the rainy season; also, individuals sometimes breed in the short dry season (summer canicula) in July and August.

At several localities species have been found breeding at different times of the year: S. baudini in March and July at Chinaja, Guatemala; S. phaeota in April and August at Palmar Sur, Costa Rica; S. puma in February and July at Puerto Viejo, Costa Rica; and S. sila in February, April, and August at El Volcan, Panama. These observations indicate only that the population breeds at more than one time in the year, but do not provide any evidence on the breeding cycles of the individual frogs. This is one important aspect of the natural history of Smilisca for which we lack data.

Breeding Sites

All members of the genus Smilisca presumably deposit their eggs in water.

Smilisca baudini usually breeds in temporary rain pools; often these are nothing more than shallow, muddy puddles. In other instances the sites are extensive ditches or large flooded areas (Pl. 8, Fig. 1). This species is an opportunistic breeder, and males gather at any of a wide variety of suitable breeding sites that are formed by torrential rains in the early part of the rainy season. Smilisca baudini nearly always breeds in open pools having bare earthen edges. Frequently congregations of S. baudini are found at such small pools, but are absent from nearby large ponds surrounded by vegetation.

Little is known of the breeding habits of S. cyanosticta, which inhabits humid forests on foothills and lowlands. Apparently its breeding sites are not unlike those of S. phaeota, which usually are pools surrounded by vegetation (Pl. 8, Fig. 2), although sometimes males of S. cyanosticta call from open muddy puddles. In uplands, where standing water is uncommon, this species breeds in quiet pools in streams.

Smilisca puma breeds in grass-choked ponds and marshes, where the males call from bases of dense clumps of grass in the water (Pl. 9, Fig. 1).

Smilisca sila and S. sordida differ noticeably from other species in the genus by breeding exclusively in streams, where males usually call from rocks or gravel bars in or at the edges of streams (Pl. 9, Fig. 2); sometimes individuals perch on bushes overhanging streams. In the streams, or parts of streams, utilized by these frogs the water is clear, shallow, and has a slow gradient; occasional males have been found calling along cascading mountain streams.

Breeding choruses composed of ten or more species of frogs are not uncommon in Middle America, but Smilisca usually breeds alone or with one or two other species and at the most five others. This tendency towards solitary breeding possibly is the result of selection of breeding sites that are unsuitable to many other species of frogs. Nevertheless, many other species of frogs have been found at the breeding sites with the various species of Smilisca; these breeding associates (Table 7) are most numerous for S. baudini, which has a broad geographic range, including a variety of habitats.

Breeding Behavior

Calling sites.--All species of Smilisca usually call from the ground, including rocks and gravel bars; some individuals sit in shallow water near the edge of the pool or stream. Sometimes males of S. baudini, sila, and sordida call from low bushes or trees near the breeding site. One S. baudini was observed calling while it was floating on the surface of a pond. Smilisca cyanosticta, phaeota, and puma call from secluded places at the edge of the water or in the water, whereas S. baudini, sila and sordida call from open situations.

Table 7.--Breeding Associates of the Various Species of Smilisca.

==============================+========+============+========+=====+=====+======== Associate |S. |S. |S. |S. |S. |S. |baudini|cyanosticta|phaeota|puma|sila|sordida ------------------------------+--------+------------+--------+-----+-----+-------- Rhinophrynus dorsalis | X | - | - | - | - | - Leptodactylus bolivianus | - | - | X | - | - | - Leptodactylus labialis | X | - | X | - | - | - Leptodactylus melanonotus | X | - | X | X | X | - Leptodactylus occidentalis | X | - | - | - | - | - Leptodactylus quadrivittatus| - | - | X | - | - | - Leptodactylus pentadactylus | - | - | X | X | - | X Engystomops pustulosus | X | - | X | - | - | - Bufo canaliferus | X | - | - | - | - | - Bufo cavifrons | - | X | - | - | - | - Bufo coccifer | X | - | - | - | - | - Bufo coniferus | - | - | X | - | - | - Bufo cristatus | - | X | - | - | - | - Bufo gemmifer | X | - | - | - | - | - Bufo haematiticus | - | - | X | - | X | X Bufo kellogi | X | - | - | - | - | - Bufo luetkeni | X | - | - | - | - | - Bufo marinus | X | - | X | X | X | X Bufo marmoreus | X | - | - | - | - | - Bufo mazatlanensis | X | - | - | - | - | - Bufo melanochloris | - | - | X | - | X | X Bufo perplexus | X | - | - | - | - | - Bufo typhonius | - | - | X | - | X | - Atelopus varius | - | - | - | - | X | X Diaglena reticulata | X | - | - | - | - | - Diaglena spatulata | X | - | - | - | - | - ------------------------------+--------+------------+--------+-----+-----+--------

Table 7.--Continued ==============================+========+============+========+=====+=====+======== Associate |S. |S. |S. |S. |S. |S. |baudini|cyanosticta|phaeota|puma|sila|sordida ------------------------------+--------+------------+--------+-----+-----+-------- Hyla boulengeri | - | - | X | - | - | - Hyla colymba | - | - | - | - | X | - Hyla ebraccata | X | - | X | - | - | - Hyla elaeochroa | - | - | X | X | - | - Hyla eximia | X | - | - | - | - | - Hyla legleri | - | - | - | - | - | X Hyla microcephala | X | - | X | - | - | - Hyla phlebodes | - | - | X | X | - | - Hyla picta | X | - | - | - | - | - Hyla robertmertensi | X | - | - | - | - | - Hyla rosenbergi | - | - | X | - | - | - Hyla rufioculis | - | - | - | - | - | X Hyla smithi | X | - | - | - | - | - Hyla staufferi | X | - | - | - | - | - Hyla walkeri | X | - | - | - | - | - Phrynohyas inflata | X | - | - | - | - | - Phrynohyas spilomma | X | - | - | - | - | - Phrynohyas venulosa | X | - | - | - | - | - Phyllomedusa callidryas | X | - | X | - | - | - Phyllomedusa dacnicolor | X | - | - | - | - | - Phyllomedusa moreleti | X | X | - | - | - | - Pternohyla fodiens | X | - | - | - | - | - Smilisca baudini | X | X | - | - | - | - Smilisca cyanosticta | X | X | - | - | - | - Smilisca phaeota | - | - | X | - | - | - Smilisca puma | - | - | - | X | - | - ------------------------------+--------+------------+--------+-----+-----+--------

Table 7.--Concluded ==============================+========+============+========+=====+=====+======== Associate |S. |S. |S. |S. |S. |S. |baudini|cyanosticta|phaeota|puma|sila|sordida ------------------------------+--------+------------+--------+-----+-----+-------- Smilisca sila | - | - | - | - | X | X Smilisca sordida | - | - | X | - | X | X Triprion petasatus | X | - | - | - | - | - Cochranella fleischmanni | - | - | - | - | X | X Centrolene prosoblepon | - | - | - | - | X | - Gastrophryne elegans | X | - | - | - | - | - Gastrophryne olivacea | X | - | - | - | - | - Gastrophryne usta | X | - | - | - | - | - Hypopachus alboventer | X | - | - | - | - | - Hypopachus caprimimus | X | - | - | - | - | - Hypopachus inguinalis | X | - | - | - | - | - Hypopachus maculatus | X | - | - | - | - | - Hypopachus oxyrrhinus | X | - | - | - | - | - Hypopachus variolosus | X | - | - | - | - | - Rana palmipes | X | - | X | X | - | - Rana pipiens | X | - | - | - | - | - Rana warschewitschi | - | - | X | - | X | X ------------------------------+--------+------------+--------+-----+-----+--------

Chorus structure.--Limited observations on some of the species of Smilisca show a definite organization of the calling behavior of individuals. Smilisca baudini and S. phaeota call in duets. This is especially noticeable in S. baudini, in which the members of a duet often call from sites separated by only a few centimeters. The call of S. baudini consists of a series of like notes (see description of call in following section); the duration of each note is about equal to the interval between notes. Normally one individual utters one note, pauses, and utters a single note again, or series of two or three notes. If there is no response, the first individual often waits several seconds or even several minutes and then repeats the call. The second individual usually responds after the first or second note of the sequence. The notes of the second individual usually are spaced so that they are emitted in the intervals between the notes of the first individual. This can be shown diagrammatically by having the figure "1" represent notes of the first individual and figure "2," the notes of the second; an empty interval is represented by "0":

1-0-1-2-1-2-1-2-1-2-1-2