Chimerothalassius Shamshev & Grootaert

Chimerothalassius Shamshev & Grootaert, 2002: 131 .

Type species: Chimerothalassius ismayi Shamshev & Grootaert, 2002, by original designation.

Diagnosis. The genus Chimerothalassius is distinguished from other parathalassiine genera by the following characters: head with gena scarcely projected below eye (Figs 12, 14, 27), mouthparts directed ventrally with fleshy labellum (e.g., Figs 14, 27), palpus elongate and narrow (Figs 12, 14), abruptly capitate apically and narrow basally (Figs 19, 27, 28), or broadly subtriangular; thorax with prosternum fused to proepisternum forming precoxal bridge, scutellum with 1 pair of strong dorsally directed setae near apex (e.g., Fig. 14); legs with fore coxa lacking field of short stout spinose setae on anterior surface, tarsomere 5 of each leg with medial apical projection, although sometimes weakly developed; wing (Fig. 22) with R 1 reaching costa before middle of wing, crossvein bm-m complete or incomplete, cell dm absent without veins M 2 and dm-m, CuA rounded, cell cua convex apically, CuA+CuP absent or vestigial, anal lobe not developed; male terminalia with hypopygium small (Figs 26, 29, 30), right epandrial lamella usually with dorsally directed ventral process (Figs 17, 24, 32), cerci symmetrical (or nearly so) and moderately short, hypoproct projected (Figs 18, 25, 33); female abdomen with apical segments retracted into segment 5 (Fig. 21), terminalia with syntergite 9+10 undivided and bearing acanthophorous setae and cercus narrowly rounded apically with prominent apical or preapical seta, or syntergite 9+10 divided and bearing acanthophorous spines and cercus pointed apically without apical seta (Fig. 21).

Remarks. Species of Chimerothalassius are known from the Caribbean, Costa Rica, New Zealand (Figs 3–7) (Brooks & Cumming 2018) and now New Caledonia (Figs 8–10) (Cumming & Brooks 2019, as “Undescribed genus [New Caledonia]”). The genus is found on rocky, stony or sandy habitats of coastal beaches (Figs 4–7) and emerged rocks in rivers (Figs 9, 10) (Shamshev & Grootaert 2002; Brooks & Cumming 2018; Cumming & Brooks 2019).