Procrocidium minutum, Grimaldi, 2016

Grimaldi, David A., 2016, Diverse Orthorrhaphan Flies (Insecta: Diptera: Brachycera) In Amber From The Cretaceous Of Myanmar: Brachycera In Cretaceous Amber, Part Vii David A. Grimaldi, Bulletin of the American Museum of Natural History 2016 (408), pp. 1-132 : 70-72

Procrocidium minutum , new species

Figures 24 , 56

DIAGNOSIS: As for genus, by monotypy.

DESCRIPTION: Based on female. Small, compact fly, thorax length 1.21 mm., wing length 2.83 mm. Head: Apparently hemispherical (based on portions preserved), width slightly greater than thorax. Eye: Occupying lateral, much of frontal and dorsal surfaces; bare; no differentiation of facets; no emargination of posterior or anterior margins; dorsomedial margins widely separated, parallel. Frons completely bare, dark, cuticle apparently dark; width nearly 2× that between outside margins of antennal bases. Ocelli on vertex of head, barely raised above frons surface, with ca. 8 small, stiff, erect setae in triangle. Face not preserved. Occiput setose, barely recessed (not strongly concave); occipital foramen large, pear shaped (vs. 8-shaped), apparently invaginated sleevelike into posterior third of head. Anterior and posterior apodemes well developed (visible through exposed and cleared walls). Occiput laterally with thick, stiff, short setae. Antenna: Small, short; scape cylindrical, pedicel subspherical, with single preapical whorl of minute setulae; 1 (basal) flagellomere present, elongate drop shaped, having minute, subapical stylus; antennal article lengths; basal flagellomere> scape> pedicel. Mouthparts: Not preserved. Thorax: Broad, apparently rather short (poste- rior portion lost). Dorsum of scutum very high, dome shaped, raised well above dorsum of antepronotum; antepronotum in approximately middle of thoracic depth as seen in lateral view. Antepronotum very well developed, laterally setose, width ca. 0.50× that of scutum; length of antepronotum 0.27× the width. Lateral cervical sclerites very large, posterior portion bulging. Scutum with very short, decumbent setulae; setulae on posterolateral portions of scutum longer. Transverse suture well developed, dorsally with apex pointed posteriad. Notopleural area just above notopleural suture with row of 3 long, stiff macrosetae; 1 such macroseta on supraalar area; all macrosetae whitish. Wing: C thick, circumambient, abruptly tapered in width midway between apices of R 4 and R 5; basicosta very small; crossvein sc-r present. Crossvein h long, lightly sclerotized; Sc reaching slightly past level of middle of wing; R 1 ca. 0.70× length of wing, apex gradually tapered to C, faint pterostigma between apices of Sc and R 1. R 1 thick; R 2+3 slightly upturned apically. Fork of R 4 -R 5 nearly symmetrical, R 4 slightly sinuous. Crossvein r-m very basal, at 0.27× length of cell d from its base. Cells br and bm nearly equal in length. M 1 and M 2 nearly parallel; m-cu strongly sinuous. Tips of CuA 1 and CuA 2 nearly meeting at wing margin. A 2 fairly long, apically evanescent. Alula small, upper calypter well developed. Anal lobe shallow. Legs: Hind coxa with well-developed peg on anterior surface. Mesotibia with long apical spur. Basitarsomere slightly longer than combined length of distitarsomeres. Pretarsus with small pulvilli, shorter than claws; empodium setiform, minute. Abdomen: Very partial. Terminalia (female): Tergite 8 apparently without dorsal apodome on anterior margin, or so short as to be unnoticeable, definitely not tongue shaped; ventrolateral portion of t7 with very fine, blond setae, shorter than setae on tergite 8. Tergites 9 and 10 separate (cannot determine whether 9 and 10 with dorsal connection); tergite 8 with dense brush of long, fine, blond setae on distal half and ventral portion. Tergite 10 narrow, with ca. 12 long acanthophorite spines on each half, spines slightly sinuous, widened apically and increased in length ventrad; spines in two even rows on posterolateral margins, dorsomedial separation between lateral rows. Sternite 8 not appearing invaginated (e.g., no sand chamber). Cerci small, shallow, lying between acanthophorites, as seen in posterior view.

TYPE: Holotype, female, JZC Bu-098.

ETYMOLOGY: In reference to the small size of the holotype.

COMMENTS: Specimen is in a small, irregularly cubic, clear yellow piece of amber 4 × 6 × 7 mm, cut from a cabochen 15 mm diameter, the entire piece of which contains no other insect inclusions. The fly is partial and portions are disarticulated (fig. 56), but sufficiently preserved to diagnose, in fact exposing some critical features. Head is still attached to the thorax, but the ventral portion (including the mouthparts) has decayed away. The wings are fully intact and connected to the thorax, but portions are folded; the venation required some reconstruction. Posterior portion of the thorax (scutum, scutellum) has decayed away. Portions and entireties of five legs are preserved, one is disarticulated at the base. The abdomen is largely decayed away, with tergites 1–3 remaining; apex of the abdomen (including the terminalia) is disarticulated from the rest of the abdomen and partially cleared, lying under the outstretched left wing near the head (fig. 56).

Figures

FIG. 24. Procrocidum minutum (Bombyliidae), new genus and species, holotype, JZC Bu-098. A. Wing. B. Detail of tip of antenna, showing minute apical style. C. Head and thorax, dorsal view, as preserved (head is tilted to show right lateral view). Portions of the head wall are lost, revealing the tentorial arms. D. Female terminalia, left lateral view, with pilosity intact. E. Female terminalia, left lateral view, with pilosity removed and showing acanthophorite spines. Panels C−E to same scale.

FIG. 56. Procrocidium minutum, new genus and species (Bombyliidae), holotype JZC Bu-098. A. Habitus, dorsal view, location of detached terminalia is indicated. B. Habitus, oblique right lateral view. C. Habitus, left lateral view.