Lathyrus neurolobus is the only member of the section Neurolobus (Shehadeh et al. in prep) and following the definition of Maxted et al. (2006), it is in Taxon Group 4 of the cultivated Grass Pea (L. sativus L.), Chickling Vetch (L. cicera L.), Sweet Pea (L. odoratus L.), Cyprus Vetch (L. ochrus (L.) DC), and a number of other cultivated Lathyrus species, including Broad-leaved Everlasting Pea (L. latifolius L.), Caley Pea (L. hirsutus L.), and Spanish Vetchling (L. clymenum L.) (Shehadeh et al. in prep).

This species is endemic to Europe, where it is restricted to a small area of western Crete, Greece. It has a small known area of occupancy (AOO = 96 km²) and extent of occurrence (EOO = 461 km²), but occurs at 33 sites, which, for the purpose of this assessment, have been treated as discrete locations. One subpopulation is known to have been lost since 1994 and all other known subpopulations are threatened by uncontrolled drainage or diversion of water. Therefore there is continuing decline in area, extent and quality of the wetland habitats as well as in the area of occupancy and number of mature individuals due to the threats of drainage and development. It therefore qualifies as Near Threatened, meeting subcriteria B1b(ii,iii,v)+B2b(ii,iii,v).

Lathyrus neurolobus is endemic to the Greek island of Crete (USDA, Agricultural Research Service, National Plant Germplasm System 2018, POWO 2023). It is restricted to an area of only 30 km² in west-east extension on the western and northwestern flanks of the Lefka Ori mountain range, currently known from the wider surroundings of Elos in the far west, and from between Alikianós, Voukoliés and Kándanos further east. Considerably further east lies a further record of L. neurolobus, discovered in 1994 by N. Turland at the margin of a peat bog near Así Goniá east of the Lefka Ori. That population is now extinct and the unique peat bog lost a few years after discovery due to habitat destruction (Fielding and Turland 2005). It mostly occurs between elevations of 160 and 800 m asl, but records have been found as low as 50 m and as high as 950 m (Bergmeier and Abrahamczyk 2007, Strid 2016).

Its area of occupancy (AOO) is 96 km² and extent of occurrence (EOO) is 461 km².

At least one peat-bog subpopulation has been lost since the mid-1990s (Fielding and Turland 2005, Kenicer and Norton 2008). However, there is no information on the population size of this species.

Almost all Lathyrus neorolobus occurrences are in the siliceous phyllite-quartzite region of Crete and are associated with three phytosociological communities.

The Adiantum-Philonotis fontana community occurs at 300–600 m asl, mostly on steep to vertical, wet or seepage slopes and embankments with shallow soil, with a west to north aspect, hence protected from insolation; in rather open to moderately dense herbaceous vegetation and mostly sparse (-25 %) bryophyte cover; characterised by Adiantum capillus-veneris, Apium nodiflorum, Carex cretica, C. troodi, Erica arborea (juveniles from adjacent scrub), Pellia epiphylla, Philonotis fontana, Samolus valerandi, and Scirpoides holoschoenus.

The Adiantion capilli-veneris community occurs at 160–800 m asl, including on steep embankments with run-off water and plain to moderately sloped sites near springs, often forming small clearings in maquis and deciduous woodland, often shaded by adjacent trees; in moderately dense herbaceous vegetation and sparse to dense bryophyte cover; characterised by Apium nodiflorum, Athyrium filix-femina, Brachypodium sylvaticum, Carex cretica, C. troodi, Crepis fraasii, Galium debile, Hydrocotyle vulgaris, Hypericum hircinum subsp. albimontanum, Oenanthe pimpinelloides, Poa trivialis subsp. sylvicola, Primula acaulis, Rubus sanctus, Samolus valerandi, Scirpoides holoschoenus, and Sibthorpia europaea.

Finally, the Scirpoides holoschoenus-Lathyrus neurolobus community occurs at (200–)500–680 m asl in damp meadows, often seepage, and similar linear structures along streams and rivers, mostly fairly dense to dense herbaceous vegetation and sparse bryophyte cover; characterised by Apium nodiflorum, Galium debile, Hydrocotyle vulgaris, Isolepis cernua, Juncus effusus, Oenanthe pimpinelloides, Ranunculus velutinus, Samolus valerandi, Scirpoides holoschoenus, and Trifolium repens.

The three community types with L. neurolobus show probably the most pronouncedly oceanic character of all vegetation types in Crete and the Aegean, with the Atlantic element strongly represented by species such as Anagallis tenella, Eleocharis multicaulis, Hydrocotyle vulgaris, Primula acaulis and Sibthorpia europaea. These community types reflect a topographic-ecological gradient of freshwater habitats, ranging from surface waters trickling down steep banks or rocks, to those with water seeping through the ground. The former may dry out but are rarely, if ever, sun-exposed; the latter are permanently damp to wet but receive in general more insolation. Lathyrus neurolobus was also found once on open damp soil where dense maquis was cleared for a new track, where germination from the seed bank seems likely.

There is an inferred continued decline in area, extent and quality of the wetland habitat.

The wetland habitats that support this species are threatened by over-exploitation for irrigation purposes, which leads to drying out. As a consequence, springs yield less water or dry out altogether, streams become torrents, and permanent rivers become merely seasonal. Furthermore, these wetlands are threatened by urban and agricultural development (Bergmeier and Abrahamczyk 2007). Lathyrus neurolobus may also be threatened by an increasingly dry climate (Kenicer and Norton 2008), and by application of fertilizers and herbicides on adjacent olive plantations.

This species is a wild relative of, and potential gene donor to the cultivated Grass Pea, Chickling Vetch, Sweet Pea, Cyprus Vetch, and a number of other cultivated Lathyrus species, including Broad-leaved Everlasting Pea, Caley Pea, and Spanish Vetchling (Shehadeh et al. in prep).

The genus Lathyrus is listed in Annex I of the International Treaty on Plant Genetic Resources for Food and Agriculture as part of the grass pea gene pool (FAO 2009).

Genesys reports nine accessions, although none are reported to be of wild origin (one natural, three other, one semi-natural/sown, four origin not specified). Two of these accessions are backed up at a second genebank, but none are duplicated and conserved in the Svalbard Seed Vault (Genesys Global Portal on Plant Genetic Resources 2018). It is therefore urgent to collect seeds of this species for long-term ex situ conservation in genebanks. According to Botanic Gardens Conservation International (BGCI 2018), this species has living collections in eight botanic gardens worldwide, although the origin and locality of the collections are not detailed in this resource (garden locations are undisclosed to protect rare and valuable plant species).

Most Cretan wetlands are included in conservation areas, especially in the Natura 2000 network (Bergmeier and Abrahamczyk 2007). Amongst these are the sites GR4340004 (Elos-Topolia) and GR4340006 (Fassas-Limni Agias), although the latter unfortunately excludes much of the catchment area of the Fassas river and also the important valley between Sembronas and Voukolies (Dafis et al. 1996). There is no robust conservation strategy for this network (Bergmeier and Abrahamczyk 2007). A relevant step would be to implement water protection areas and to provide legal and factual means to control, and set an end to if need be, water exploitation both from public and private lands. There is a need to develop a population estimate, assess populations trends, as well as the extent and scale of current threats and establish a monitoring protocol.

The species was globally assessed as Vulnerable in the 1997 Red List of Threatened Plants (Walter and Gillet 1997).