Phthinia cascadica
Phthinia cascadica can be distinguished from all other Phthinia by the strongly-developed, digitate, posteriorly-directed, posterodorsal lobes of the gonocoxites which are unique within the genus. The only other taxon with distinctly dorsal lobes on the gonocoxites is P. parafurcata Oliveira & Amorim (described from Chile), but the dorsal lobes in this species are mesally-, rather than posteriorly-directed.
Male. Body length: 6.2–8.4, 7.4 [7.6] mm (n=8).
Head. First flagellomere longer, approx. subequal the length of flagellomere 2.
Thorax. Laterotergite with several setae. Scutellum with 4 stronger bristles (although sometimes only 2–3 apparent and sometimes all setae are shorn off).
Legs. First tarsomere of foreleg approx. 2.5 times length of foretibia, first tarsomere of midleg approx. 1.7 times as long as midtibia, and first tarsomere of hind leg approx. 0.7 times as long as hind tibia. Apex of hind tibia with apex ventrally produced into a keel-like point bearing the outer tibial spur apically. Hind tibia with 2–6 minute anterior setae, 17–27 minute dorsal setae, and 8–10 minute posterior setae (N=2); midtibia also with a small number of minute anterior and dorsal setae.
Wings. 4.2–5.5, 5.0 [5.3] mm (n=8). Membrane with macrotrichia; microtrichia also present between more widely spaced macrotrichia. C extending about 1/3 of the distance between R5 and M1; Rs about 1/4 length r-m; r-m subequal to slightly longer than stem of M; medial fork complete; M1 distinct basally. A1 diverging only slightly from stem of CuA.
Abdomen. Terminalia beige-brown to light brown, contrasting with darker color of abdomen. Cerci short, lobate, apically rounded with small setae. Hypoproct about as long as wide, much longer than more dorsally situated cerci; posterior margin with a broad, shallow, v-shaped emargination. In dorsal view, gonocoxite developed dorsally beyond point of articulation of gonostylus into an apical (posteriorly directed) digitate, apically rounded, setose lobe devoid of strong spine-like setae. Gonostylus with five lobes; two mesally-directed lobes, one apically-directed lobe, and two spine-like posteriorly-directed lobes (the latter best seen in ventral view); the former three lobes are less sclerotized, more or less apically rounded, and covered with setae over most of surface; apically-directed lobe with strong setae. The two strong, subequal, spine-like, posteriorly-directed lobes are primarily bare and setose only basally. In ventral view, aedeagal complex protruding ventromedially beyond ventromedian margin of gonocoxites; triangular, apically acute.
Female. Similar to male.
(after Fitzgerald & Kerr, 2014)
Phthinia cascadica is recorded from about 38ºN latitude California north to Vancouver British Columbia with all records in the extreme western parts of the these states/provinces (while we did not examine any specimens from Washington, this species undoubtedly occurs there). Specimens have been collected nearly at sea level, up to 1,097 m, in habitats including coniferous woodlands (including coastal redwood forests in northern California), and mixed woods in semi-wild open spaces on the edges of towns. This species was reared from a pupa found suspended by threads in a hollow cavity on the underside of a rotten deciduous log, with the overhead canopy being made up of Big Leaf Maple, Elm, and Cherry trees; the lower surface of the rotten log, including the small hollow in which the pupa was suspended, was covered with a white encrusting fungus. Considering the records, it seems likely that the species is at home in coniferous or deciduous woods as long as an appropriate fungal host can be located. Adults have been swept from a log pile (mix of coniferous and deciduous logs), taken in Malaise traps, and attracted to a porch light. The seasonal distribution is late May–July and September–December (the majority of these fall records occurring within October–November).
(after Fitzgerald & Kerr, 2014)
(after Fitzgerald & Kerr, 2014)