Eulychnia ritteri

Accepted name and position of the Peruvian lineage

Eulychnia ritteri Cullmann is an accepted species in POWO, native to Arequipa in Peru. In older literature, it appears as E. breviflora subsp. ritteri and E. iquiquensis subsp. ritteri. Distinguishing taxonomic rank also matters when interpreting conservation assessments published under a broader name. [2-WWW] [Pauca-Tanco et al. 2021]

Merklinger and colleagues' genomic data place E. ritteri as the sister lineage to all Chilean taxa studied. The plastid tree places it closer to the Chilean E. breviflora group. Both analyses indicate distinctness of the Peruvian material, while disagreement over its precise position may result from historical gene flow or incomplete sorting of ancestral DNA variants. The authors consider these explanations as alternatives. [Merklinger et al. 2021, p. 190–194]

Structure and flower visitors

In the field assessment, the species has a tree-like growth form, with a trunk and branched, ribbed stems. Flowers are pink and open during the day, and fruits are fleshy and orange. Individual plants may simultaneously bear buds, open flowers and fruits. This was recorded during monitoring at Vizcachani. It represents overlapping developmental phases rather than a uniform flowering date established for all populations. [Pauca-Tanco et al. 2021, p. 078–080, 082–084]

Flower visitors observed included hymenopterans such as Lasioglossum sp., melyrid beetles and butterflies of Pyrgus sp. The observations identify insects visiting flowers. The effectiveness of their single visits in pollination and seed production was not measured in this study. [Pauca-Tanco et al. 2021, p. 084]

Five populations in Caravelí Province

Studies from September 2017 to October 2018 covered five populations in the Yauca, Chala and Cháparra districts of Caravelí Province. These were Vizcachani, La Tajo, Cementerio, Febres and Huaccllaco. Their total occupied area was estimated at around 63.62 ha. The largest, Vizcachani, occupied 24.5 ha, and the smallest, Cementerio, around 0.018 ha. These are mapping results from the study period. [Pauca-Tanco et al. 2021, tab. 1, p. 081]

Plants grew on very dry rocky terrain, on moderately or steeply inclined slopes. Ocean fog periodically reached some places, while rain was sporadic. Lichens on plants were recorded in Febres and Huaccllaco. Differences in local moisture input and population location provide the background to their different conditions, but the study did not determine how much water cacti absorbed from fog. [Pauca-Tanco et al. 2021, p. 082–084]

Plant structure in Vizcachani

In October 2018, plants were counted on three 10 × 100 m plots. Accessible patches of Vizcachani with relatively high density were selected. Seedlings were defined by a height below 10 cm, young plants by larger size and absence of reproductive signs, and adults by branched structure and evidence of flowering or fruiting. Plants without living stems were counted separately. [Pauca-Tanco et al. 2021, p. 080, tab. 2, p. 082]

The three patches contained 166 plants in total, including 6 seedlings, 40 young plants, 94 adults and 26 dead plants. The predominance of adults and few seedlings describe the structure of this selected sample. A one-off classification by size and reproductive signs provides information on the current condition. Recruitment and survival rates of successive generations require repeated censuses of the same plots. [Pauca-Tanco et al. 2021, tab. 2, p. 082]

Animals using stems and fruits

Nests of the bird Pseudasthenes cactorum were found on the plants. The rodent Lagidium peruanum ate the fleshy fruits. The cactus therefore provides both nesting sites and food. The authors suggest possible seed dispersal by the rodent, but did not conduct an experiment recovering seeds and assessing their viability. [Pauca-Tanco et al. 2021, p. 084–085]

Threats to separated populations

Cementerio lies near the built-up area of Chala. In 2018, only 14 adult plants were found there, with no renewal through young specimens in the surveyed portion. Mining activity, quarries and roads were described near other sites. Threat type depends on locality. Loss of a small patch can affect a substantial part of one isolated population. [Pauca-Tanco et al. 2021, p. 082, 085–086]

Based on distribution and identified threats, the authors of the 2021 article proposed category EN, Endangered. This is an assessment presented in the study, based on 2017–2018 data. An older assessment of a more broadly circumscribed E. iquiquensis does not automatically determine the status of the now separate E. ritteri. Its own range, site condition and continuity of recruitment matter when assessing this lineage. [Pauca-Tanco et al. 2021, p. 085–086] [2-WWW]

Collection material and cultivation under cover

Retaining locality of origin and former names in plant documentation helps link collections to Arequipa populations. General principles for columnar cacti in containers are presented in the genus account. The field account of E. ritteri concerns habitats, population structure and conservation. [Merklinger et al. 2021] [Pauca-Tanco et al. 2021] [1-WWW]

Related articles

Materials from the author's archive

The species also appears in Konrad Szychowski's private material archive. [Romulski b.d., file p. 4]