Myzinum obscurum Fabricius
Creators: name: Kimsey, Lynn S.
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Tiphiidae
Myzinum
Myzinum obscurum

description: Myzinum obscurum (Fabricius)
Fig. 5, 21; Map 7
Tiphia obscura Fabricius 1805:233. Holotype female; “ Carolina ” (COPENHAGEN).
Plesia nigripes (Guérin Méneville) 1837:577. Holotype male; no locality given (PARIS). This species was listed by Krombein (1951) as a synonym, but the species was moved into the genus Poecilotiphia by Gorbatovsky (1981).
Plesia fuliginosa Lepeletier 1848:581. Holotype male; “Pensylvanie” (PARIS, lost?). Synonymized by Krombein (1938).
Elis berlyi Brimley 1927:238. Holotype female; USA: South Carolina, Charleston (WASHINGTON). New synonymy.
Male.―Body length 20 mm. Head: hypostome forming right angle in profile; frons punctures small, contiguous, becoming larger towards midocellus; ocellocular distance 1.3x interocellar distance; mandible with small subsidiary tooth; flagellomere I length 1.7x breadth; flagellomere XI length 2.3x breadth. Thorax: mesopleuron with faint omaulus, punctures subcontiguous; propodeum transversely rugosopunctate; fore and hindcoxa unmodified; midcoxa inner margin angulate or dentate. Metasoma: tergum VII flat, smooth apicomedially. Genital capsule (Fig. 21): paramere ventral lobe 3x as broad as long, with five spines extending along apical one-fifth, dorsal lobe marginal setae fewer than six, about three-fourths as long as volsella; volsella parallel-sided, flattened ovoid in cross-section, rounded apically, setose apically, four-fifths as long as paramere ventral lobe; aedeagus apical bulb 1.5x as broad as shaft below. Color: black, with yellow markings;; clypeus yellow; inner eye margin with yellow band along inner margin; antennal lobe with yellow spot; pronotum with broad anterior and posterior yellow bands; mesopleuron with large anterior and smaller posterior yellow spots; scutum, scutellum and metanotum with medial yellow spots; tegula yellow; coxae, femora and tibiae with yellow band or spot; tarsi yellow; propodeum with large yellow lateral spot; metasomal terga I–VI with narrow transverse posterior yellow band, sterna II–VI with elongate posterolateral yellow spot; wing membrane untinted. Ve s t i t u r e.―silvery.
Female.―Body length 15–22 mm. Head: frons punctures contiguous from near antennal lobes to midocellus; ocellocular distance 2.2x interocellar distance; vertex punctures 2–4 PD apart; hypostomal angle forming right angle in lateral view; flagellomere I length 0.9x breadth. Thorax: pronotum dorsal surface with contiguous, somewhat striatiform punctures without tiny interpunctures; propodeum laterally densely transversely ridged, posterior surface with fine ridges radiating dorsally and laterally from petiole; foretarsal rake with 7 spines. Color: black, with yellow markings, with brown on antenna, mandible, legs and metasoma; head with yellow band on inner and posterior eye margins; antennal lobe yellow; pronotum with anterolateral yellow spot; mesopleuron with anterior yellow spot; tegula with yellowish margin; metanotum yellow medially; propodeum with small sublateral yellow spot; metasomal terga I–V with lateral yellow spot, sternum II sometimes with small basolateral yellow spot; forewing membrane brown-tinted, somewhat darker along costal margin. Vestiture: silvery.
Distribution (Map 7).―Eastern USA: Delaware: Newcastle Co.; Florida: Alachua, Collier, Levy, Santa Rosa Counties; Georgia: De Kalb, Richmond Counties; Illinois: Scotts, Williamson Counties; Kansas: Pattawatomi, Riley Counties; Kentucky: Beckenridge, Edmonson Counties; Maryland: Montgomery Co.; Mississippi: Lafayette Co.; Missouri: Boone, Henry, Lincoln, Warrenton Counties; Henry, Lincoln Counties; New Jersey: Burlington Co.; North Carolina: Buncombe, Moore, Watauga Counties; Ohio: Clermont Co.; Oklahoma: Atoka Co.; South Carolina: Charleston Co.; Texas: Cameron, Frio, Tyler Counties; Virginia: Fairfax, Rockbridge, Williamsburg, York Counties; Washington, D.C. 63 females and 4 males were studied.
Discussion.―Diagnostic features for this species include the lobate male midcoxa, features of the male genitalia, the dark coloration, and the large, somewhat striatiform punctures on the female pronotum. The male paramere dorsal lobe is nearly half the width of the paramere in side view, with only five apical spines and the volsella is ovoid in cross-section and appears broadest medially. Myzinum obscurum occurs in the eastern U.S. from Illinois and Maryland south to eastern Texas and Florida.
Myzinum beryli Brimley is here synonymized under obscurum. Comparison of the type females of beryli and obscurum revealed that the only distinction between the two was the extent of tiny interpunctures on the pronotum. Otherwise the types shared the same dark coloration of the wings and body, sculpturing of the propodeum, ocellocular distance and dimensions of the flagellomeres. All of the males associated with beryli by Brimley and Krombein actually share features typical of male obscurum including the dentate midcoxa.
No justification could be found for the two beryli subspecies, parksi and patei, described by Krombein. Examination of his type material revealed the two subspecies to be structurally identical with carolinianum, mostly distinguished in his paper by differences in coloration and minor variations in the shape of the paramere. Modifications of the male genitalia of the two subspecies are the same as variation observed in carolinianum. Finally the subspecies and carolinanum occur in the same regions.
description: Published as part of Kimsey, Lynn S., 2009, Taxonomic purgatory: Sorting out the wasp genus Myzinum Latreille in North America (Hymenoptera, Tiphiidae, Myzininae), pp. 30-50 in Zootaxa 2224 on pages 47-48, DOI: 10.5281/zenodo.190193