Why are yellow and black Riodinids rare?

Unfortunately no one knows. These Riodinids are excellent mimics of day flying Geometrid

cyllopoda            xantho

moths like the Cyllopoda species (left) and Xanthyris flaveolata (right) so it could be their fate as Batesian mimics to be less common than their models for success as a species. Usually rare species of butterflies have very specialized ecological needs or the larvae feed on something (plants or animals) that has a spotty local distribution. Often rare species fly where they are not easily observed, like in the canopy or they have a short flight activity or are crepuscular. The following are accounts of some of these rare species.


Colaciticus johnstoni  (Dannatt, 1904)  Top – male from Pto. Inirida, Colombia (Courtesy: Pedro Alejandro Sarmiento Diaz)    Bottom left – male, Villavicencio, Colombia. Bottom right – female, Villavicencio.

C_johnstoni_Pto_Indirida   C_johnstoni_Pto_Indirida3

IMG_1965a  IMG_5636a

This species is rarely seen because it’s a canopy dweller.  David Ahrenholz  observed this species in Ecuador flying at  a height of about 10 meters. Here in Villavicencio they were all seen between 2 and 3 meters high in trees. Their normal behavior probably changes when they fly through small forest fragments. Five males and one female were recorded during a 2 year period, all during the rainy season. The photos of the male taken by Pedro Alejandro Sarmiento Diaz in Puerto Inirida document the second locality known for this species in Colombia.


 

Colaciticus seitzi Salazar, Constantino & Rodriguez, 2010    The male holotype (Coutesy of Julian Salazar E.) Left – dorso. Right – ventral.

Colaciticus_seitzi_HOLOTYPE2  Colaciticus_seitzi_HOLOTYPE

This is the only known specimen. It was collected on the east slope of the Cordillera Central near Fresno, Tolima at 800 meters. The species description is in the following publication:

                   Rodriguez, Gabriel, Julián A. Salazar-E., and Luis Miguel Constantino. 2011.                          “DESCRIPTION OF NEW SPECIES AND NEW RECORDS OF RIODINIDS                             (LEPIDOPTERA : RIODINIDAE ) FOR COLOMBIA.” Bol.cient.mus.hist.nat                            14 (2): 215–237.   download


Pachythone xanthe  H. Bates, 1868  Top -female, Tachira, Venezuela. (Courtesy: Andres Miguel Orellana)  Middle – female, Villavicencio, Colombia. Bottom – left, male; right. female, Villavicencio.

P1010468  P1010466

IMG_6551a  pachythone_xanthe1

In the field the males of this species are very difficult to tell apart from a Mesene, especially the females of M. nola. The males were frequently seen at the study site but the female was a mystery. Identifying the first female was a problem, none of the experts consulted were sure of what species it was. It appears the female of xanthe was unknown until these females were captured.  In the middle picture you can see the green colored eggs through the very thin integument of the female. The early stages and hostplants of all the species of Pachythone are unknown.


Pachythone bicolor (Godman & Salvin, 1886)                                                              All  photos of specimens from Villavicencio, Colombia.  Top left – dorsal,  Top right ventral view.  Bottom left-lateral view and right a head shot of the punk hairdo.

P_bicolor

IMG_2329  bicolor_head

This interesting creature is one of those rare examples of a species that has a wide distribution but is rarely encontered anywhere. It has been collected in Guatemala, Panama, Colombia and Brazil but there are only 8 specimens in collections. Bicolor was described in 1886 and was only known from the type specimen for almost 80 years until a few specimens were collected in the 1960’s in Brazil, Guatemala in 1992 and recently in Colombia. The genus has changed over the years, first it was in Lepricornis, then Pheles and now Pachythone. The Colombian specimens were found in a fragment of secondary forest just outside of Villavicencio during the rainy season. They made short flights, perching between 1 and 2 meters high on the underside of tree leaves with their wings outspread. So far the female is unknown.

For a recent revision of the species see:

Dias Silva, Fernando Maia, Diego Rodrigo Dolibaina, Carlos Guilherme Costa Mielke, Olaf Hermann Hendrik Mielke, and Mirna Casagrande Martins. 2015. “Description of Two New Species of Pheles Herrich–Schäffer, [1853] and Notes on the Taxonomic Position of Two Species Hitherto Included in the Genus (Riodinidae: Riodininae).” Zootaxa 3981 (2): 275–283.  download

 

 

 

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The survey method and first results

The first few months of 2012 were spent investigating the forest, learning to identify the Riodinids and studying their habits. Then a survey method had to be chosen. It had to be not overly complicated to do, e.i. no excessive collecting or measurements, but still produce informative and reliable results. The most adequate appeared to be a Pollard transect count (Pollard, 1977) modified by Caldas and Robbins (2003). The protocol is walking a fixed transect through the study area for a predetermined time and recording the species and numbers observed, the modification being that you can net individuals for identification purposes. This step was important for the difficult to identify Riodinids like the brown and white Nymphidium-Synargis-Juditha group  and the red and orange Mesene. A 150 m existing path through the woods was chosen for the transect. This path traveled the length of the stream and crossed over to the opposite side, continuing for half the length of the site. The remaining 1/4 of the area was too difficult to survey, being swampy in part and with a very closed vegetation over the rest.

IMG_8644

Practice surveys were done during the last two weeks of April, 2012. After several trials I found that the time to walk the transect was 40 minutes. Everything looked in order, so I started the survey on May 1, 2012.  Two separate walks were made each sample day. The first between 9am and 11am and the second between 11:30am and 1:30pm.  Except during the dry season the second daily survey almost always added a few species not seen during the first run, but care was taken not to duplicate counts. The counts of the most common species seen in the two daily surveys were averaged or the highest count used. Due to the small size of the butterflies and the habits of many, the effective observation radius was about 2 meters. After each daily survey the data was entered on an Excel spreadsheet with the species names in columns and the days in rows. Each entry was either 0 for not observed or the number of individuals seen. Every month a new sheet was started.

Fig.1  Below is a summary of the number of species seen each day in the first year. The sampling rate was 26.6 days/month; 319 days were sampled. An index of  the number of species observed/sample days was calculated for each month to compare trends between the months.excel_days_2012

 

Fig.2     All the raw data of the numbers of species observed per day.yr_1_Page_2

Fig. 3    Species/month. The Y axis is the monthly mean of species observed.yr_1_Page_3

Summary

For the whole 12 month period 78 species were observed with 19 (24%) as singletons. Combining singletons and doubletons, 32% of the species were rare. Running the data in EstimateS (Colwell, 2013) to estimate species richness, a Chao1 mean of  108.08 (CI 87.53-172.95) was calculated. From the Sobs and Chao 1 we can estimate that only 72% of the species in the local assemblage were observed, 30 species went undetected. Considering the intensive sampling effort, 30 undetected species appears high but then again only 1 hour and 20 minutes were spent sampling on any given day, just 10% of the daylight hours and the subjects we are dealing with are very good at concealing themselves.

Species richness increased from May, the early part of the rainy season, until it peaked in the middle of September and then declined and stabilized during Oct. and Nov. A further drop in the daily number of species occurred in December which coincides with the beginning of the dry season. The lowest levels of richness were seen in the dry season (Jan.-Feb) and this low level continued through the next months as the rainy season began. Only a few species reproduce and maintain populations in the forest throughout the year, immigration, emigration and extinction drive the fluctuations in species richness.

 

References

Caldas, Astrid, and Robert K Robbins. 2003. “Modified Pollard Transects for Assessing Tropical Butterfly Abundance and Diversity.” Biological Conservation 110: 211–219.

Colwell, R. K. 2013. EstimateS: Statistical Estimation of Species Richness and Shared Species from Samples , Version 9.1, Persistent URL <purl.oclc.org/estimates>.

Pollard, E. 1977. “A Method for Assessing Changes in the Abundance of Butterflies.” Biological Conservation 12 (2): 115–134.

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Juditha caucana

This gallery contains 9 photos.

(click on photos for a larger view in a separate tab) Juditha caucana (Stichel, 1911) Some species of Juditha are very similar, like caucana, molpe and azan, and are difficult to identify . The photos on the Butterflies of the Americas website ( link ) … Continue reading

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Calospila emylius

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  Calospila emylius (Cramer, 1775) male female This species is common and both males and females are often seen at flowers throughout the study site during morning hours. The males become territorial between 2-4 pm and perch at specific sites on the outlook … Continue reading

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Nymphidium lisimon

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Nymphidium lisimon (Stoll, 1790) Lisimon is the dominant species at the study site and was never absent a single day during four years of the survey. To try to explain the factors contributing to this species success, the following characteristics might be considered: Small … Continue reading

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Riodina lysippus

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Riodina lysippus (Linnaeus, 1758) This species is one of the few Riodinids commonly found outside the forest. They are often seen on country roadways feeding on flowers or perching on vegetation in the sun. So far only Inga vera ( Fabaceae) … Continue reading

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Anteros acheus

This gallery contains 16 photos.

Anteros acheus (Stoll, 1781)   The acheus caterpillars were found feeding on a common species of Miconia, a Melastomataceae near Villavicencio, Colombia. I noticed the feeding damage on a young plant and found a shelter formed by a curled piece … Continue reading

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About the study site

IMG_8627

The east slope of the Cordillera Oriental near Villavicencio is an area of high biodiversity and endemism. The forest is categorized as very humid tropical lowland forest with rainfall averaging 4,400 mm per year. The dry season occurs during the January and February when it usually rains less than 100 mm/month. The transition to the rainy season starts around the middle of March and the rains taper off in December. Average yearly daily temperature is 26.5° C. The river systems are all Orinoco drainage up to the Sierra de la Macarena.

The study area is a little fragment of tropical forest located behind the lab (my house) a few kms from the town of Villavicencio, Colombia at 04° 03′ N, 73° 42′ W and 495 m above sea level. The wooded area is 30 m wide x 100 m long and covers an intermittent stream. The site is isolated on the two long sides by an agricultural land matrix but the linear forest strip is continuous to the north following the stream. This protective tree cover over the stream plus some hedgerows here and there produce a faunal corridor that leads to a 30IMG_8484 hectare fragment of forest on a neighboring farm 800 m away. The neighbor’s forest is then connected by corridors to the larger forest on the slope of the mountain some 2 km distant. The forest canopy is between 15 and 20 meters in height and consists of about a dozen old trees with a diameter greater than 50 cm scattered throughout the site and a larger number of younger trees with a diameter of 10-30 cm. The large edge/area ratio allows entrance to pioneer species like Cecropia, Vismia and especially Miconia which are a common species in the forest. In the past, before the survey was started, the understory plants were clear cut as is custom in the region but now the uncut understory is a luxuriant carpet of plants. In the low swampy areas grow thickets of  Calathea (Marantaceae) and in the higher areas are many species of Rubiceae, Solanaceae, Araceae, ferns and grasses.

Weather data is collected on a daily basis. Rainfall is measured with a wireless Acu-rite rain gauge and the temperature and humidity in the forest is transmitted from a Lascar data logger via Wifi to my computer.

IMG_8491a

Looking at the edge of the woods from the stream

studysite3a

A satellite view of the area around the study site. The lighter green areas are agricultural land, mostly pastures, and the dark green areas are forest fragments. For reference, the dark patch of forest above the study site is about 30 hectares.

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