Sciadocerinae (Schmitz, 1929)

Grimaldi, David A., 2018, Basal Cyclorrhapha In Amber From The Cretaceous And Tertiary (Insecta: Diptera), And Their Relationships: Brachycera In Cretaceous Amber Part Ix David A. Grimaldi, Bulletin of the American Museum of Natural History 2018 (423), pp. 1-97 : 1-97

Sciadocerinae indet.

Figure 50

SUMMARY: A unique male specimen (AMNH Bu-1376) of a minute species (~ 1.7 mm body length), which is not being formally described since critical structures are not visible (i.e., arrangement of frontal setae, palp size, empodium, presence/absence of stridulatum, base of M vein). This species is like Prophora dimorion in appearing to have a frontal sulcus (this is barely visible), acrostichals in single row, 1 pair of large dorsocentral setae (vs graded row), 2 pairs of scutellars, presence of proscutellum, and few leg macrosetae. It differs from Prophora by significantly smaller size; head with finer, shorter frontal setae; 2 (vs. 3–4) pairs of notopleural setae; scutellar setae upright (vs. posteroclinate); no postalars (vs. 1); microtrichiae completely absent from wing membrane (vs. with some at apex); base of M appears spectral, though not fully visible (vs. present, tubular, though not sclerotized). Further, the male abdomen and genitalia are substantially different: in Bu-1376 segments 6–7 with constriction between them, tergite 7 bulbous, epandrium asymmetrical (vs. symmetrical in Prophora ); male terminalia very asymmetrical, surstyli apparently absent or so small as to not be visible (vs. symmetrical, with pendulous surstyli).

GENERAL DESCRIPTION: Body short, length ~ 1.7 mm total length, broad, with relatively few setae. Head about same width as thorax. Antenna with arista dorsal, preapical. Head setae barely visible, appears to have 1 small pair of supraantennal interfrontals ; 1 large pair of orbitals; 1 pair of ocellars; 1 pair of verticals; postoculars relatively short. Scutum arched, short; 1 short row ~6 acrostichals; 7–8 dorsocentral setae, not graded (1 large pair of prescutellar dorsocentrals; other dorsocentrals small, about same size as acrostichals). Two long notopleural setae, 1 supraalar, no postalars. Proscutellum present, narrow; scutellum short, wide, with 2 long, upright pairs of setae. Pleural region not visible. Wing short, broad (L/ W 1.7), venation very similar to that of Hennigophora robusta , except that base of M appears spectral, not tubular; membrane devoid of microtrichia. Abdomen very short and broad at anterior end, width of segments 2 and 3 about same as thorax ; abdomen tapered in width to segment 6 (= 0.25× width of segment 2), forming constriction between segments 6 and 7. Tergite 7 slightly asymmetrical, larger than tergite 6; tergite 9 (epandrium) well developed on right side; terminalia asymmetrical, shifted mostly to right (component structures not discernable); surstylus not apparent. Legs with very few macrosetae ; mesotibia with apical pair of long, spurlike setae.

The specimen is largely complete, but some legs and segments are disarticulated. It is in a dark piece of amber that also contains a layer of sand grains, stellate trichomes, and particulate debris. A piece of bark or plant fragment lies under the fly; this and the sand grains prevent viewing the front of the head, prolegs, and some other areas.

Figures

FIG. 50. Minute, undescribed Sciadocerinae (Phoridae) in Burmese amber AMNH Bu-1376. A. Dorsal habitus, as preserved (some podomeres are disarticulated; portions of wing and body obscured). B. Detail of wing base.