The under-rock guild of nemerteans from Lough Hyne, south-west Ireland was recorded during a long-term benthic survey of the marine reserve. From 2004 to 2014, common nemerteans were recorded annually in late summer for ten historical monitoring sites (each 10 m of shoreline); more comprehensive surveys were completed in 2012 (4126 low-intertidal to shallow-subtidal rocks were turned) and 2014 (1289 rocks turned) with supplementary information in 2015. The bootlace worm, Lineus longissimus, was the most abundant nemertean species. It was significantly more abundant at the extremely shallow East Castle site than the other nine sites; peak populations (across all ten sites) occurred in 2012. The Lusitanian nemertean Paradrepanophorus crassus was abundant after 2007. To date, 13 nemertean species were recorded with numerous new records for the lough, including Tubulanus annulatus, Micrura purpurea, Ramphogordius sanguineus, Micrella rufa and Emplectonema gracile. Three additional nemertean species were previously recorded, indicating that at least 16 species occur in the lough. Given the low densities and paucity of comprehensive earlier records, we are not able to ascertain definitely whether these species are new incursions or if sparsely distributed residents have increased.

The interstitial hoplonemertean Ototyphlonemertes duplex, originally described from Naples, is collected for the first time on the Spanish Mediterranean coast at the Cabo de Gata Natural Park (Mediterranean, south-east Spain). Morphological data and pictures of this species are provided.

The occurrence of the hoplonemertean Emplectonema neesii in the north-east Atlantic has been reported from Iceland to France. This paper provides the first record of E. neesii in Galicia (north-west Spain), possibly the most southern location, if the previous records under this name from the Mediterranean referred to a different species. Morphological data and pictures of this species are provided.

The warm-water nemertean species Paradrepanophorus crassus, described from Mediterranean shores, was first recorded in Lough Hyne, County Cork, Ireland in 1931 by Renouf. This large nemertean that forms membranous tubes under low intertidal to shallow subtidal rocks has increased in frequency, particularly from 2009 to 2012 with peak values of 0.26 specimens per metre of shoreline. Eggs were noted within the membranous tube of one specimen collected in June 2012. Furthermore, based on digital photographs of specimens, the striped nemertean species Punnettia splendida was also noted in September 2011; this is a new species record for Lough Hyne.

The first successful captive maintenance of living terrestrial Geonemertes nemertines is reported. Behavioural observations are described, including the first data on diet in this genus. The species G. pelaensis is found to be a predator of small molluscs. In 1907 the Seychelles population was described as a distinct species, G. arboricola, largely on the basis of its arboreal habit. Recent field data from the Seychelles islands of Mahé and Silhouette confirm the tendency towards arboreal behaviour.