Nematodes Berthold, 1827

Otto, Robert L., Muona, Jyrki & Córdoba-Alfaro, Jim, 2023, A new genus and sixteen new species of false click beetles (Coleoptera: Eucnemidae) described from the Heredia Province of Costa Rica with several additional records from the Osa Peninsula and Panama, Insecta Mundi 2023 (991), pp. 1-36 : 32

Genus Nematodes Berthold, 1827

Diversity and distribution. Nematodes is a moderately large group consisting of 48 species. Five described species are distributed in eastern North America, north of Mexico. Twenty-three species are found in the Neotropical region, including the Caribbean Islands. One species occurs throughout much of Europe and Russia. Two species are distributed along the eastern coastline of the Australian continent. One species is present on the African continent. Nine species are represented in Southeast Asia, including Japan. At least seven undescribed species are known in the Neotropical, Oceanic and Southeast Asian regions. In Costa Rica, in addition to the newly described species, there are 6 other species present: Nematodes biarti Bonvouloir ( Figure 67 ), N. conjunctus Bonvouloir ( Figure 68 ), N. cuneatus (Guérin-Méneville) ( Figure 69 ), N. cylindricus (Laporte) ( Figure 70 ), N. mannerheimi Bonvouloir ( Figure 71 ) and N. mexicanus Chevrolat ( Figure 72 ). Both Nematodes mexicanus and N. conjunctus have not been observed in the province of Heredia, but are present elsewhere in Costa Rica and therefore are included in the identification key.

Diagnosis. Apical margin of frontoclypeal region feebly trilobed and more than twice as wide as the distance between antennal sockets; antennal grooves absent; male protarsomere I simple with basally curved sex combs; tarsal claws simple; tarsomere IV excavate-emarginate; metacoxal plates medially 3.0–6.0 times wider than laterally; last visible ventrite strongly produced; lateral surfaces of meso- and metatibiae with setae and transverse rows of spine combs; metathoracic episterna parallel-sided; male aedeagus dorsoventrally compressed, with laterally attached secondary lateral lobes; median lobe simple, with moderately and narrowly bifurcate apices; lateral lobes simple, entire; aedeagal flagellum simple ( Muona 1993, 2011; Otto 2016).

These diagnostic characteristics, especially the presence of excavate-emarginate tarsomere IV and parallel-sided metathoracic episterna will distinguish the group from any other genera within the tribe Nematodini .

Figures

Figures 67–70. Costa Rican Nematodes species. 67) Nematodes biarti, dorsal habitus. 68) Nematodes conjunctus, dorsal habitus. 69) Nematodes cuneatus, dorsal habitus. 70) Nematodes cylindricus, dorsal habitus. (Scale: 67 = 1.0 mm; 68–70 = 5.0 mm)

Figures 71–74. Costa Rican Nematodes species. 71) Nematodes mannerheimi, dorsal habitus. 72) Nematodes mexicanus, dorsal habitus.73) Nematodes apicalis sp. nov., dorsal habitus. 74) Nematodes apicalis sp. nov., ventral habitus. (Scale: 72–74 = 1.0 mm; 71 = 5.0 mm)