Diptera: Stratiomyidae)
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Systematic Entomology (1986) 11, 377-387 Parhadrestiinae, a new subfamily for Parhadrestia James and Cretaceogaster Teskey (Diptera: Stratiomyidae) NORMAN E. WOODLEY Systematic Entomology Laboratory, USDA ABSTRACT. A new subfamily of Stratiomyidae is proposed for Parhadrestia James and Cretaceogaster Teskey (fossil from Upper Cre- taceous Canadian amber). Evidence is delimited that indicates that this subfamily is the sister-group to all other known stratiomyids. Taxa in the subfamily are systematically described, including a new species, Parhadrestia curico, from Chile. Introduction character states has been determined by James (1975) described the stratiomyid genus outgroup comparisons. Elsewhere (Woodley, in Parhadrestia based on a single species he had preparation) I have shown that the Xylomyidae discovered from Chile, P.atava. He placed the are clearly the sister-group to the Stratiomyidae, genus in the Beridinae presumably because it so they have been used as the functional possesses an abdomen with seven larger seg- outgroup in this study. In the same work I have ments, a plesiomorphic feature in the family. In discussed the autopomorphic character states connection with a study of the world genera of used to characterize stratiomyids, so they are not Beridinae, I have re-examined the genus, and repeated here. Also in that work I discuss the have concluded that it is actually the sister-group characters which support the cladistic placement to all known extant stratiomyids. Also, of the Chiromyzinae, Beridinae, and remaining re-examination of the only known specimen of subfamilies of Stratiomyidae as shown in Fig. 1, Cretaceogaster pygmaeus Teskey (1971), a fossil so this argumentation is also omitted in the pre- from the Canadian amber (Upper Cretaceous), sent paper and these characters do not bear indicates that it is cladistically related to numbers in the figure. In the following discus- Parhadrestia. Following a discussion of these sion, the initial statement is the apomorphic relationships, I propose a new subfamily for character state for each character in question. these two genera. Terminology of morphologi- (1) Hypandrium at least partly fused to cal features follows that of McAlpine (1981). gonocoxites. In all known stratiomyids except Parhadrestia and Cretaceogaster, the hypandrium (ninth abdominal sternite) is at Cladistic relationships least partly fused to the gonocoxites. Only in Fig. 1 presents a cladogram showing the charac- some Chiromyzinae and Beridinae is it partly ters used to support the hypothesized relation- free; in other stratiomyids it is completely fused ships between Parhadrestia, Cretaceogaster, and to the gonocoxites. In Parhadrestia (Figs. 13, other known stratiomyids. The polarity of the 18), the hypandrium is completely free from the gonocoxites, and is apparently free in Cre- taceogaster. Teskey (1971: Fig. 4) has illustrated Correspondence: Dr Norman E. Woodley, Sys- tematic Entomology Laboratory, IIBIII, ARS, the male genitalia of the fossil, and a view of USDA, c/o U.S. National Museum of Natural Parhadrestia from the same angle is remarkably History, NHB 168, Washington, DC 20560, U.S.A. similar. The structure of the hypandrium is quite 377 378 Norman E. Woodtey midtibial spur lost 9A 1 midtibial spur 9 1 flagellomere aA 2 flagellomeres 8 Mg absent 7 palpi one-segmented 6 AS6.7 reduced tergal grooves + larval setae tufted ? ? aedeagus trifid ? scutellar spines mouthparts reduced cell cup truncate 5 R4 8R5 subparallel 4 8AS reducedllost 3 parameres reduced 2 hypandrium fused ii i FIG. 1. Cladogram showing relationships of the tww genera of Parhadrestiinae to other Stratiomyoidea. Character statements at thc left indicate the apomorphic character state. Unnumbered characters are not discussed in the text (see Woodley, in preparation). Question marks indicate characters which cannot be viewed in the fossil holotype of Cretaceogaster. Open squares indicate plesiomorphic character states, filled squares indicate apomorphic character states, and half-filled squares indicate that both character states occur in that lineage. Purhudrestiinae, primitive Stratiomyidae 379 different In the Xylomyidae, because their geni- nite, which is often modified in various ways talia are highly modified from the general such that its shape is often species specific (e.g. plesiomorphic form found in ‘lower Webb, 1984: 251). Brachycera’. Figures in Nagatomi & Tanaka (4) Wing veins R4 and R5 nearly parallel (1971) indicate that the hypandrium is quite apically. This character state is unique to reduced in size and is fused to the gonocoxites at Parhudrestia and Cretaceogaster. In its anterior corners in xylomyids. Fusion of the Parhadrestia (Fig. 8) the branches of R4+s are hypandrium to the gonocoxites is clearly very long, and are parallel for much of their apomorphic, as noted by Stuckenberg (1973). length. In Cretaceogaster (Fig. 9) the position of (2) Fused parameres reduced in size. In the fork is quite similar, but the branches are Purhadrestia, the parameres of the aedeagal shorter and parallel only near their apices. In all complex have apparently become fused and other stratiomyids and in Xylomyidae, R4 is form a dorsal hood over the aedeagus (Figs. 15- shorter to much shorter than R5, and is strongly 17), much like that found in Tabanoidea (see divergent from it, ending considerably anterior McAlpine, 1981, for a discussion of parameres to the wing apex. within the Diptera). This fusion is evidently (5) Apical section of wing vein CuA, (closing independent of that found in Tabanoidea, as the cell cup) short and straight. In both Parhadrestia parameres are not fused in Xylomyidae (see and Cretaceogaster (Figs. 8, 9), vein CuA, is RozkoSny, 1973: Figs. 21, 25; McAlpine, 1981: short and straight, forming a truncate closure of Fig. 2.122). In addition, they are not mem- the anal cell (cell cup). In all other known branous in Purhadrestia. In the remaining stratiomyids and xylomyids, vein CuA, is stratiomyids this structure has become markedly slightly to strongly arcuate, so that the end of cell reduced in size and essentially forms the small cup appears rounded, or sometimes acute, but structure by which the aedeagal complex is never truncate. This is perhaps the strongest attached to the gonocoxal apodemes. It seems evidence for the close relationship of unlikely that the lateral lobes of the trifid aedea- Parhadrestiu and Cretaceogaster. gal complex found in many stratiomyids are (6) Palpi one-segmented. In Parhudrestia, the homologous with parameres as thought by palpi are much reduced in size and are one- RozkoSny (1982), because neither Parhudrestia segmented. This structure cannot be seen in Cre- or Chiromyzinae have a trifid aedeagal complex. taceogaster. In most other stratiomyids and In the Chiromyzinae the aedeagus is apparently xylomyids, the palpi are large and clearly two- a simple tube (see Nagatomi & Yukawa, 1969), segmented. They are one-segmented in although the apex may be vaguely lobed Chiromyzinae, but in members of this subfamily (Nagatomi & Yukawa, 1969: Fig. 10). Much I have examined they are strongly ovoid to remains to be learned about the male genitalia of nearly spherical, not small and peg-like as in Chiromyzinae, and this knowledge will be Purhadrestia. Presumably this is not syn- important in interpreting the structures of the apomorphic in these two primitive groups, but aedeagal complex in more apomorphic more knowledge of the poorly known stratiomyids. Chiromyzinae is needed before this can be eluci- (3) Eighth abdominal sternite in male very dated. In a few other scattered taxa of reduced or lost. In nearly all stratiomyids, the stratiomyids a one-segmented palpus is present, eighth abdominal sternite of the male is com- but these are clearly derived from related genera pletely unsclerotized, only membrane remaining which have two-segmented palpi. In one genus in its place. In some Beridinae and a few of Xylomyidae, Xyfomya,the palpi are one-seg- Chiromyzinae, small vestiges of sclerotization mented. They are not reduced in size. Presuma- are still present medially, but in other members bly this state is autapomorphic, for the genus, as of these subfamilies the sternite is lost. In other xylomyids have two-segmented palpi. Parhadrestia the eighth sternite is quite large, (7) Wing vein M3 absent beyond discal cell. In although somewhat smaller than the eighth both Parhadrestiu and Cretaceogaster (Figs. 8, tergite. In relative size, it is much larger than in 9), vein M3is absent. In most other stratiomyids any other known stratiomyids. This region of the and in all xylornyids M3 is present. It is absent abdomen cannot be seen in Cretaceogaster. from some Chiromyzinae and Beridinae, and all Xylomyidae have a relatively large eighth ster- Pachygastrinae (which are grouped in ‘other 380 Norman E. Woodley subfamilies’ in Fig. 1). In the first two sub- tibia. A single spur is found only in a few families, intermediate states can be seen in Chiromyzinae and in scattered Beridinae, as which Mi is shortened. This character is well as all known Antissinae and in the enigmatic apparently quite plastic, and loss of M3 has evi- genus Exodontha Rondani. dently occurred independently several times. (8) Antennal flagellum strongly fused, two flagellomeres present. Character state distribu- PARHADRESTIINAE new subfamily tion discussed under 8A below. (8A) Antennal flagellum composed of a single Diagnosis. Small, drab stratiomyids with a flagellomere. In Cretaceogaster, the antennal short abdomen and rather long wings. Defining flagellum is largely fused, with a large basal autapomorphic states (numbered as above) are flagellomere and a short, style-like apical (6) one-segmented palpi, (7) wing vein M3 flagellomere. Teskey (1971: Fig. 1) showed the absent beyond discal cell, (4) fork of wing vein flagellum as a single flagellomere, but my obser- R4+5nearly parallel apically, with R4 ending vations indicate that two flagellomeres are pre- nearer and the wing apex than in other sent. Parhadrestia (Figs. 2, 4, 6) has the KS Stratiomyoidea, (5) wing vein CuAz straight, flagellum entirely fused into a single thus the end of cell cup truncate, and (8) the tlagellomere.