Guapinannus tenuis, sp. n.

(Figs 4, 7, 9)

Holotype. Male. COSTA RICA: Unknown locality, no date provided, collector unknown, 1♂ (UCR _ ENT 00014617) (INBIO).

Etymology: Named for the slender vesica after “tenuis” Latin for slender.

Diagnosis: Recognized by the large body length (2.06 mm), narrow C+Sc (black arrow), distal margin of rc1, rc, and tc cells distinctly double s-shaped (white arrow) (Fig. 4), relatively long s-shaped vesica, and absence of anophoric process (Fig. 7).

Description: Male: Total body length 2.06 mm; length from posterior margin of pronotum to posterior wing margin 1.49 mm; greatest width across pronotum 0.69 mm; wing missing. General coloration: uniformly pale. Vestiture: Dorsum with sparse setae, setae short; setae on posterior margin of forewing long. Structure: Head: Eye about one third as high as head; muscle scars large. Thorax: Anterior pronotal margin straight, posterior margin slightly concave; pits on pronotum large, in distinct clusters; scutellum in dorsal view abruptly narrowed to tip, tip rounded. Forewing: With outline elongate oval; membrane contributing about one third of forewing length, posterior distal margin rounded, vein-tracing areoles on proximal part of wing absent; C+Sc uniformly narrow; distal process of R weakly developed; An1 wing organ on corium weakly developed; rc1 about 3 times as long as wide, much wider anteriorly; rc about 5 times as long as wide; tc about 3 times as long as wide; part of An1 and Cu forming posterodistal margin of tc of similar width as other veins; distal margin of rc1, rc, and tc cells s-shaped; rc2- 3 almost triangular; cub removed from wing margin; dc1 with basal portion relatively wide and short. Legs: Claws long. Genitalia (Fig. 7): Pygophore without lobe on right side; vesica with between half and one loop, not reaching right pygophore margin, thick at midpoint, tapering to acute tip, close to apex slightly s-shaped; anophoric ridge with process, process short, with single lobe curved, tip pointed; right paramere straight, tapering, basal process broad; left paramere straight, tapering, basal process broad.

Female: Unknown.

Collecting method and habitat: Unknown.