Grzegorzekia quercus Fitzgerald, 2019

Fitzgerald, Scott J., 2019, The Nearctic species of Grzegorzekia Edwards (Diptera: Mycetophilidae), Zootaxa 4623 (3), pp. 163-174 : 167-169

Grzegorzekia quercus Fitzgerald n. sp.

Figs. 7–9 , 12

Diagnosis. In general habitus this species is virtually identical to G. kerri n. sp. and can only be distinguished by the male and female terminalia. The combination of the presence of a mid-tibial sense organ (as Fig. 6 ), abdominal tergites with narrow pale posterior bands (as Fig. 1 ), and the structure of the terminalia ( Figs. 7–9 ), including the shorter, cow-horn-like gonocoxal lobe, will distinguish males of G. quercus n. sp. from all congeners. Females can be distinguished by the combination of abdominal tergites with narrow pale posterior bands (females of G. collaris may have pale coloration only at the anterolateral areas of some or all of tergites 2–7) and sternite 8 longitudinally divided medially and with two patches of strong spine-like setae apically ( Fig. 12 ), but not distinctly produced posteriorly into a pair of apically truncated lobes in ventral view.

Description. Male. Body length: approx. [5.0] mm (n=1). Head. Brown with thin grey pollinosity and short setae. Three ocelli, lateral ocelli less than their diameter distant from the eye margin. Antennae ~1.5 times as long as head + thorax. Pedicel and scape short, thick, beige and brown, scape with grey pollinosity. Fourteen elongate, dark brown flagellomeres shortening distally, basal flagellomere about four times as long as wide and beige at base. Thorax brown, scutum sub-shining dark brown with thin grey pollinosity both laterally and forming narrow longitu- dinal median and dorsocentral stripes converging posteriorly. Short, light brown acrostichal and dorsocentral setae, and longer lateral setae, present. Pleura brown, with thin grey pollinosity. Antepronotum with setae, propleuron and pleural sclerites, including laterotergite and mediotergite, bare. Legs. Femora beige with dark joints, tibia light brown with dark brown joints, tarsi brown. Mid tibia slightly swollen just above half way point with a thin whitish elongate sensory area along dorsal surface (as Fig. 6 ). Legs without strong setae, fore tibia without macrosetae, mid tibia with one tiny anterior seta, hind tibia with several tiny anterior, dorsal, and posterior setae. Hind basitarsus slender, elongate, parallel-sided, approximately fourteen times as long as wide. Tibial spurs 1:2:2. Tarsal claw with a basal tooth, empodia undeveloped. Wing (essentially as in Fig. 2 ). [5.0 mm] (n=1). Hyaline with dark maculae in the following areas: around radial cell, base of Rs, r-m, and stem of M, along length of CuA, narrowly along most of the length of all longitudinal veins starting at apical third of wing, and narrow border along C beyond wing tip. Veins brown, all with dorsal setae except: Sc, base Rs, R 2+3, base and stem of M. Sc ending at about the level of the base of Rs, sc-r ending near apex of Sc, at or slightly beyond level of posterior fork. Radial cell rectangular, base Rs slightly shorter (about 2/3 the length) r-m, R 4+5 distinctly bowed distally. Stem M ~ 2X as long as r-m. Posterior fork beginning basal to level of medial fork, before level of base of r-m, near level sc-r; base of M 4 narrowly interrupted (detached from stem at level of fork). Abdomen. Brown with narrow, bright-beige band on posterior edge of tergites 1–8. Terminalia ( Figs. 7–9 ). Tergite nine broader than long with broad shallow v-shaped emargination on posterior edge ( Fig. 9 ). In lateral view, gonocoxite section II tapered to a single rounded lobe. In posterior view, an additional dorsomedially-directed lobe bearing an apicodorsal comb of closely-set spine-like setae (see “com” Fig. 8 ); comb of spine-like setae not visible in dorsal or lateral views. Aedeagal guide and aedeagus large, dominating terminalia in ventral view ( Fig. 7 ) and strongly projecting posteroventrally in lateral view ( Fig. 8 ). Aedeagal guide broad, rectangular ( Fig. 7 ). Aedeagus in dorsal view, subrectangular, membranous, with a pair of dark internal rods, and apex with a slight indentation. Paramere triangular in lateral view ( Fig. 8 ) and subrectangular in dorsal view ( Fig. 9 ). Gonocoxal lobe cow-horn-like, short, stout basally, tapered to a point apically ( Figs. 7–9 ). Gonostylus absent. Gonocoxite section I not clearly distinguished from gonocoxite section II, but may be represented by area essentially bare of setae making up most of gonocoxite in ventral view ( Fig. 7 ). Gonocoxite section III a pair of large curved, scoop-like, ventrally setose lobes ( Fig. 8–9 ). Cerci fleshy, densely setose, subrectangular, but with dorsoapical outer corner narrowed into small lobe with single large, black, spine-like seta ( Fig. 9 ); the lobe and strong seta could be homologous to the epiproct sensu Chandler (1999 Fig. 16) which, in G. collaris , bears a strong black setae and is associated with the apical margin of the cerci. Hypoproct not identified.

Female. Most aspects essentially as in male, except as follows. Body 6.0 mm (n=1), wing 6.0 mm (n=1). Midtibial organ absent. On one wing Sc terminates beyond sc-r, but before reaching C. Cerci beige, basal segment elongate, rectangular, apical segment small, rounded. Sternite 8 longitudinally divided medially, sternite not prolonged into a pair of lobes posteromedially, but with two patches of 8–9 black, spine-like setae on each side of medial cleft ( Fig. 12 ).

Biology. In November 2016 a single adult male was found resting on the underside of a rotten, fallen branch of Oregon White Oak (Quercus garryana) about 4 inches in diameter that had the upper surface covered with bark and thick moss, and the lower surface free of bark/moss and partially covered with a white sheet-like encrusting fungus ( Fig. 13 ); the adult specimen was not teneral so it was unclear whether it had emerged from this habitat or if it was just resting there. Within a few days a female (again, fully hardened and not teneral) was found nearby (~100 meters from the initial collecting site) resting on the underside of a second oak branch which was similar in size and age, with the upper surface completely free of bark/moss, and with white encrusting fungus on parts of its lower surface. This female is tentatively associated with the male of G. quercus n. sp. based both on the timing and proximity of the collection and on the fact that the female terminalia of this specimen differ from those of the other two known Nearctic species. Attempts to rear mycetophilid larvae observed on the underside of several oak branches (some on the fungus and some on the bare wood) resulted in specimens of Trichonta sp., Phronia braueri Dziedzicki , Mycetophila ocellus Walker , and Mycomya sp., so it remains unclear if the larvae of G. quercus n. sp. are developing on rotten fallen oak branches and associated fungi. However, it seems likely that the oak branches could have been the site of larval development for several reasons. Firstly, in addition to finding the adults on oak branches, the only previous biological information on the genus comes from a rearing of G. collaris larvae from the surface of wet rotten wood ( Chandler 2015) and it would therefore not be surprising to find other members of the genus also developing on rotten wood. The sites where adults of the new species have been collected are best characterized as low elevation patches of mixed woods that are predominated by broad leaf trees and interspersed with areas cleared for pasture, agriculture, and residential development (Willamette Valley Ecoregion). It is also noteworthy that at least G. bushyae is also associated with broad-leafed woodlands that either included or were predominated by oaks ( Chandler 2015). Oregon White Oak savannas and woodlands, a habitat once widespread in the Willamette Valley (the site of the type locality), are among the most endangered ecological communities in the Pacific Northwest ( Noss et al. 1995, Vesely & Tucker 2004, Garmon 2006). Considering this, it would be of further interest to better understand the ecological requirements of G. quercus n. sp. and its association, if any, with Oregon White Oak.

In contrast to Palearctic congeners which, based on published records, appear to be active during the summer months, G. quercus n. sp. has thus far been collected only during the fall (November) which is part of Oregon’s lengthy rainy season (the lower field that can be seen in Fig. 13 is part of the flood plain of the Mary’s River, which sees seasonal flooding and was partially flooded at the time the photo was taken).

Distribution. Presently known only from the Willamette Valley Ecoregion of Oregon.

Etymology. The specific epithet is taken from the Latin “quercus ” (oak) as the only known specimens of this species were found resting under the rotten, fallen branches of Oregon White Oak.

Type Material. Holotype: Male , point-pinned [ OSAC], USA: Oregon: Benton Co., Corvallis, 1440 SW Allen Street, 17 Nov. 2016, 44.551105, -123.271617, resting under rotten fallen Oregon White Oak branch, S. Fitzgerald [white label] / HOLOTYPE, Grzegorzekia quercus Fitzgerald [red label] / Oregon State Arthropod Collection , OSAC _0001002069 [white barcode label], terminalia dissected . Paratype: USA: Oregon: Benton Co.: 1 female [ JSL-UOC], same data as HT except 1460, SW Allen St. , 20 November 2016, 44.550864, -123.270505, resting under rotten fallen Oregon White Oak branch.

Figures

FIGURE 1. Grzegorzekia kerri n. sp., holotype male, habitus. Scale bar = 5 mm.

FIGURE 2. Grzegorzekia kerri n. sp., wing. Scale bar = 1 mm.

FIGURE 13. Typical habitat of G. kerri n. sp. and G. quercus n. sp. with mature Oregon White Oak (Benton Co., Corvallis, Oregon, USA); the holotype male of G. quercus n. sp. was found resting under the fallen, moss covered branch in the foreground (indicated by white arrow).

FIGURES 7–9. Grzegorzekia quercus n. sp., male terminalia. Scale bar = 0.5 mm. 7. Ventral view. 8. Lateral view. 9. Dorsal view. Abbreviations: aed, aedeagus; aed g, aedeagal guide; cer, cerci; com, comb of spine-like-setae; gc II, gonocoxite section 2; gc III, gonocoxite section 3; gc lb, gonocoxal lobe; par, paramere; T9, tergite 9.

FIGURES 10–12. Female terminalia, ventral view. 10. G. collaris. Scale bar = 0.33 mm. 11. G. kerri n. sp. Scale bar = 0.5 mm. 12. G. quercus n. sp. Scale bar = 0.25 mm. Abbreviations: S8, sternite 8.

FIGURES 3–6. Grzegorzekia kerri n. sp., 3–5. male terminalia. 3. Ventral view. Scale bar = 0.5 mm. 4. Lateral view. Scale bar = 0.5 mm. 5. Dorsal view. Scale bar = 0.5 mm. 6. Male mid-tibial sensory organ, dorsal view (anterior setae seen at left). Scale bar = 0.26 mm. Abbreviations: aed, aedeagus; aed g, aedeagal guide; cer, cerci; com, comb of spine-like-setae; gc I, gonocoxite section 1; gc II, gonocoxite section 2; gc III, gonocoxite section 3; gc lb, gonocoxal lobe; par, paramere; to, tibial organ; T9, tergite 9.