Microgramma bifrons

[Derrick]

Unfortunately this program scrambles my climate charts, so I have removed them but they are probably of little importance because climate can vary enormously over short distances in mountain habitats.

 

Microgramma bifrons (Hooker) David Bruce Lellinger published in The American Fern Journal 67(2) 1977.  Basionym Polypodium bifrons
William Jackson Hooker published in Filices Exoticae 52, 1859. Synonym Solanopteris bifrons (Hooker) Edwin Bingham Copeland
published in American Fern Journal 41L 75, 128, 1951.

  Description: Plants epiphytic, stems 1-2 mm thick, bearing spherical, swollen, ant-inhabited tubers to 2.5 cm in diameter, stem scales sparsely scattered, circular, 0.2-0.4 mm in diameter, somewhat bicolorous (two coloured), castaneous (chestnut coloured), with rather narrow, orange (rarely whitish) margins. Leaves strongly dimorphic (two formed), sterile form 4-10 cm long, 1-3 cm broad; lamina (leaf blade) elliptic, thin herbaceous and pinnately lobed.  Fertile form reaching 6-18 cm long, but only 0.3-1 cm broad, margins sinuate (wavy) to weakly lobed.  Sporangia (spore producing organs) grouped into large (4-5 mm), discrete, round or oval sori (sporangia clusters) placed in a single series between leaf costa (its central rib) and leaf margins.

  Habitats: On shrubs, small trees and high branches of tall trees in wet forests at 180-900 m.(591-2953 ft.) hence warmer altitudes than M. bismarckii. Note the exposed positions. Range:  Colombia; Ecuador, and Peru. Records: Ecuador; Sucumbios Province, Aguarico, at 237 m. (778 ft.)  This is probably in nearby Cuyabeno National Park inland and north of Puerto Aguarico on the Aguarico River.  Much of the park is tropical flooded forest with high rainfalls in the wet season and consequent humidities of 85-95 %.  A dry season starts from December until March and the rainy season runs from April until July followed by a moderate rain season between August and November.  Annual temperatures hover around 25°C (77°F.)  Also in Moreno-Santiago Province at 322 m. (1056 ft.),  Pastaza Province at 400 m. (1312 ft.), Napo Province, Archidona alongside the Rio Inchillaqui.  The climate in Tena City situated about 10k south of Archidona is surprisingly cooler than the hot, humid, lower Amazonian jungle to the east because it sits at 500 m. (1640 ft.)  Rainfall is very high all year with annual averages of about 4.36 m. (14 ft.), with heaviest falls through April, May, and June.  This gives an average of about 14 inches (355.59 mm.) per month with a mean of about 2/3 of an inch for the frequent rainy days (see following chart.)  Archidona itself sits at about 605 m. (1985 ft.) so probably its temperatures are fractionally cooler again.  Means (averages) do not of course show absolute highs or lows but Archidona certainly has mild, humid conditions.

  Ecology: Ants would find terrestrial nesting very unsuitable in annually flooded forests so plants that provide arboreal homes above highest water levels would be particularly beneficial.  We will see this trend in a few other ant-house species.

Note that all of these sites are inland, on the Amazonian side, east of the high Andes.

  Records: Collections are recorded throughout much of inland Peru to the south.  Again these are east of the high Andes and range from the Amazonas Region in the far northeast of Peru, to the Madre de Dios Region in the far southeast as well as the Cuzco Region, west of Madre de Dios.

Amazonas Region, Bagua Province, (near?), Bagua City at 600 m (1969 ft.)  Bagua City sits at an altitude of about 440 m. (1,440 ft.) and its temperatures indicate quite mild regimes with cool to cold nights.  Condorcanqui Province; one record at a warm 200 m (656 ft.)  Madre de Dios Region; Manu Province, at a cooler 565 m. (1854 ft.)  Puerto (Port) Manu City for which there are climate statistics sits at only 296 m (971 ft.) on the Rio Madre de Dios (Mother of God River) so its temperature ranges will be warmer than the actual collection site probably in Manu National Park upriver, yet there are similarities between the graph below and the following statistics.  Climate records for Cocha Cashu Biological Station, Manu National Park at 400 m. (1312 ft.).  Rainfall recorded between September 1976 and August 1977 was 2100 mm (83 in.)  At Pilcopata a site higher in Manu National Park at 650 m (2133 ft.) hence closer to a record at 565 m.(1854 ft.), the mean annual rainfall from 1971-1980 was 3929 mm (155 inches.) so higher than Puerto Manu’s 3089 mm. (122 inches.)  July is the driest month with an average rainfall of 188 mm. (7.4 inches.)  Because of the higher altitude it may be a little cooler here than at Cocha Cashu Biological Station.  Higher up in the Andes rainfall drops again, and temperatures fall significantly to average a few degrees above zero.  Fog is common all year round in montane forest regions.  The rainy season is from October to April with an average monthly rainfall of more than 200 mm. (8 inches.)  Rainfall decreases from early May to late September to less than 100 mm (4 inches) per month.  There is some variation of air temperatures during the year; the coldest month is June with an average of 11.1°C (52⁰F.) the hottest month is October at 25.4°C. (78°F.) 

Peru Continued: Pasco Region, Pasco Province, Oxapampa area in the Chanchamayo Valley, there are collection records at 300 m (984 ft.), 380 m. (1247 ft.), 491 m (1611 ft.), 670 m (2198 ft.), 700 m. (2297 ft), and 890 m. (2920 ft.)  This valley ranges from the cold to cool, high mountain forests of the Selva Alta or Ceja de Selva (literally eyebrow or fringe of the mountain) down to lower, altitude, hence much warmer rainforests.

The climate is usually humid and cloudy, with average temperatures around 15-25°C and rainfall of 1500-2000 mm (5-6.6 ft.) but it can be cool to cold at night at higher altitudes.  Oxapampa Town itself sits at a cool altitude of 1,814 m (5,951 ft.) thus much higher than the collection records for this species.  However, the small German derived settlement of Pozuzo some 80k further down the valley sits at only 738 m (2421 ft.) so its weather statistics should give a far better indication of collection site climates.  Note that Pozuzo has a fractionally drier ‘winter’ season if such a word is useful so near to the equator.  Pozuzo has an interesting history.  In conclusion it would appear that this species prefers primarily mild conditions especially overnight allied with consistent rainfalls with perhaps some epiphytically drier months.