Species

BackPseudechinosoma nodosum Hustache, 1936

Pseudechinosoma nodosum Hustache, 1936

True weevil (English); Gorgulho-casca-de-noz (Portuguese)

  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Class: Insecta
  • Order: Coleoptera
  • Family: Curculionidae
EN Endangered
IUCN Red List Status:

Countries of Occurrence:
Portugal - Azores

Archipelago(s):
Azores

Reviewer/s:
Danielczak, A.

Contributor/s:
Amorim, I.R.

Facilitators / Compilers/s:


Assessment Rationale:

Pseudechinosoma nodosum is an endemic species present in Flores, Faial, Pico, S. Jorge, Terceira, S. Miguel and Santa Maria islands (Azores, Portugal). It has a large extent of occurrence (EOO = ca 33,700 km²) and small area of occupancy (AOO = 100 km²). The species is common and known from at least 13 locations comprehending seven fragmented subpopulations. Most area of occurrence is protected and it is well preserved. In the past, the species has probably strongly declined due to changes in habitat size and quality. One of the most important ongoing threat to this species is the spread of invasive plants changing the structure of the forest floor, decreasing the habitat quality and with potential impacts on several subpopulations. Based on Ferreira et al.(2016) the habitat will further decline as a consequence of climate change. Based upon the small area of occupancy and the ongoing impact of invasive plants it is assessed as Endangered.

Geographic Range:

Pseudechinosoma nodosum is an endemic species present in Flores, Faial, Pico, S. Jorge, Terceira, S. Miguel and Sta. Maria islands (Azores, Portugal) (Borges et al. 2010), known from Natural Forest Reserves of Caveiro and Mistério da Prainha (Pico); Pico Pinheiro (S. Jorge); Pico Galhardo and Terra Brava (Terceira); Graminhais and Pico da Vara (S. Miguel) and Pico Alto (St. Maria). The extent of occurrence (EOO) is ca 33,700 km² and the maximum estimated area of occupancy (AOO) is 100 km².

Regions:
Portugal - Azores
Extent of Occurrence (EOO):
33700 (km2)
Area of Occupancy (AOO):
100 (km2)
Elevation Lower Limit:
400 (m)
Elevation Upper Limit:
1200 (m)
Biogeographic Realms:
Palearctic
Presence:
Extant
Origin:
Endemic Azores
Seasonality:
Resident

Population:

P. nodosum is a widespread and particularly abundant species in native and few patches of exotic forests. The species currently has a decreasing population density due to the spread of the invasive plant Hedychium gardnerianum that is changing the structure of the forest and the cover of bryophytes and ferns in the soil with impacts on the species. This species is assessed here as severely fragmented as at least 50% of its population can be found in subpopulations that are 1) smaller than would be required to support a viable population, and 2) separated from other habitat patches by a large distance. In fact, the species occurs in fragments that are isolated in a matrix of pastures.

Habitat and Ecology

The species occurs in native forests (mainly dominated by Juniperus brevifoliaLaurus azorica and Ilex perado spp. azorica) and Cryptomeria japonica plantations  in Flores, Faial, Pico, S. Jorge, Terceira, S. Miguel and Sta Maria islands (Azores), with an altitudinal range between 400 and 1200 m. This is an univoltine species. Adults and larvae are herbivores and feed on plant tissues. This is a dead wood specialist (i.e. saprophagous).

Major Threat(s):

In the past, the species has probably strongly declined due to changes in habitat size and quality (Triantis et al. 2010; Terzopoulou et al. 2015). One of the most important ongoing threat to this species is the spread of invasive plants changing the structure of the forest. Based on Ferreira et al. (2016) the habitat will further decline as a consequence of climate change (habitat shifting & alteration and increasing number of droughts).

Conservation Actions

The species is not protected by regional law. Its habitat is in regionally protected areas (Natural Parks of Pico, S. Jorge, Terceira, Pico, S. Miguel and Santa Maria). The Terceira Natural Park administration is currently starting control measures of the invasive plants. Further spread of invasive plants needs to be stopped in most islands order to avoid any future declines of the species. Degraded habitats should be restored and a strategy needs to be developed to address the future threat by climate change.  A habitat management plan is needed and anticipated to be developed during the coming years. Further research is needed into its ecology and life history in order to find extant specimens in more native forest sites and obtain information on population size, distribution and trends. It is also necessary a monitoring plan for the invertebrate community in the habitat in order to contribute to perform a species potential recovery plan in some of the islands. An Area-based Management Plan is needed for some of the  subpopulations, namely in Santa Maria and S. Miguel. A monitoring every ten years using the BALA protocol will inform about habitat quality (see e.g. Gaspar et al. 2011).