Phthinia Winnertz, 1863: 779 Description. Coloration. Vertex brown; face and clypeus light brown to beige; labella beige; four palpomeres beige. Scape and pedicel beige; flagellomeres brown to dark brown. Thorax beige to brown (sometimes ruddybrown dorsally); scutum sometimes with a hint of dorsocentral stripes. Wing hyaline and unmarked. Halter beige basally, brown distally. Legs beige-brown to brown, generally more pale basally becoming darker distally. Abdomen brown to dark brown; terminalia not significantly contrasting color of abdomen or paler (sometimes bright beige-yellow) and noticeably contrasting color of abdomen. Head. Vertex setose; two or three ocelli, aligned; lateral ocelli larger than mid-ocellus. Eyes setose. Scape and pedicel setose particularly in apical half; 12–14 elongate flagellomeres with dense pale trichia; flagellomeres in contact with each other (with no distal neck); length of first flagellomere varies slightly among species (may be subequal or longer than second flagellomere). Face and clypeus setose; four visible palpomeres. Thorax (Figs. 2, 31). Pronotum with strong setae. Scutum shining, short, strongly arched, covered with scattered small setae and rows of stronger dorsocentrals and laterals; scutellum setose, typically with 2–4 stronger bristles (although when 4 sometimes only 2–3 apparent and sometimes all setae are shorn off); the apical pair strongest. Mediotergite with several setae laterally; laterotergite with or without setae; remaining thoracic sclerites bare. Legs. Legs very long and slender (Fig. 1); first tarsomere of foreleg much longer than foretibia (approx. 1.5 to 2.5 times as long). Tibial spurs 1:2:2, short, approx. as long as tibial width at apex. All legs with dense, minute, irregularly arranged trichia. Anteroapical depressed area of foretibia present. Mid- and hind tibia with a row of minute anterior and dorsal setae; hind tibia sometimes with minute posterior setae; foretibia without rows of setae. Basal half of midtibia with slender, elongate, less-sclerotized, slit-like, sensory organ in both sexes. Wings (Figs. 3, 32). Membrane moderately to densely covered with macrotrichia (though an undescribed Oriental species apparently lacks macrotrichia (Ševčík 2008)); microtrichia present and irregularly arranged (not in distinct longitudinal rows); microtrichia sometimes unevenly dispersed (e.g. P. fasciata Freeman has microtrichia only close to the veins). C extending variable distance beyond apex of R5; Sc complete, bare dorsally, reaching C before base of Rs and sometimes before base of r-m; sc-r present, at approximately the halfway point of Sc; R1 long, reaching C near wing tip; R4 absent; Rs oblique, shorter than to subequal to r-m; r-m longer, shorter, or subequal to stem of M; medial fork complete, but base of M1 sometimes faint (Fig. 32); stem of medial fork shorter than fork; origin of medial fork before origin of cubital fork; cubital fork complete, forking distal to fork of M; CuA2 sinuous; A1 ending far from wing margin, fading out before level of Cu fork, diverging slightly (Fig. 3) to greatly (Fig. 32) from stem of CuA. Abdomen setose, long and slender. Male terminalia rather variable. Cerci short, lobate, apically rounded with small setae (Fig. 11) to elongate, apically acute, and each with a very strong apical seta (Fig. 35). Hypoproct forming a pair of rounded setose lobes ventral to cerci (Fig. 35); may be much smaller than cerci (Fig. 35) or developed into a pair of lobes longer and broader than cerci (Figs. 4, 6). Parameres forming medially fused dorsal plate; thin and lightly sclerotized to heavily sclerotized and strongly developed (Fig. 36). Homology of components of the sperm pump require further investigation, but several sclerotized structures including at least an ejaculatory apodeme are present. Tergite 9 ranging from a very narrow sclerotized strip just anterior to cerci (Fig. 27) to welldeveloped (Fig. 35) and either simple in shape or with lateral lobes (as in P. parafurcata Oliveira & Amorim). Gonocoxites ventromedially fused (Figs. 24, 29) or not fused (Fig. 7); sometimes with variously developed lobes posteriorly (Figs. 39, 40), posterodorsally (Figs. 4, 5), posteroventrally (Figs. 22, 24), or on inner ventromedial surface of gonocoxite as a hypandrial lobe (Fig. 19). Gonostylus articulating on dorsomedial surface (Fig. 23, 36) or at posterior apex of gonocoxites (Figs. 9, 28); gonostylus variously developed, but often with multiple lobes. Female terminalia with two-segmented cerci (Figs. 8, 38); apical segment fleshy ovate. Gonapophysis 9 apically acute or digitate; shape useful in distinguishing species.

Published as part of Fitzgerald, Scott J. & Kerr, Peter H., 2014, Revision of Nearctic Phthinia Winnertz (Diptera: Mycetophilidae), pp. 301-325 in Zootaxa 3856 (3) on page 304, DOI: 10.11646/zootaxa.3856.3.1, http://zenodo.org/record/251697