Allotrichoma Becker

Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2012, Revision of New World Species of the Shore-fly Subgenus Allotrichoma Becker of the Genus Allotrichoma with Description of the Subgenus Neotrichoma (Diptera, Ephydridae, Hecamedini), ZooKeys 161, pp. 1-101 : 17-18

Genus Allotrichoma Becker

Allotrichoma Becker 1896: 121 [type species: Hecamede lateralis Loew, by original designation]; 1926: 19 [revision, Palearctic species]. Aldrich 1905: 624 [Nearctic catalog]. Jones 1906: 181 [catalog]. Williston 1908: 307 [generic key]. Hendel 1930: 135-136 [comparison with Discocerina and Hecamede ]; 1936: 102, 104 [comparison with Discocerina ]. Cresson 1942: 108-109 [review of Nearctic fauna]. Wirth and Stone 1956: 467 [species, California]. Wirth 1965: 736 [Nearctic catalog]; 1968: 5 [Neotropical catalog]. Cole 1969: 397 [discussion, species of western United States]. Mathis 1986a: 129-130 [description]; 1991: 6 [description and discussion]. Mathis and Zatwarnicki 1995: 149-156 [world catalog].

Diagnosis.

Allotrichoma is distinguished from other genera of the tribe Hecamedini by the following combination of characters: small to moderately small shore flies, body length 1.15-2.95 mm.

Head: Wider than high in anterior view; frons wider than high, entirely and mostly densely microtomentose, with vestiture of mesofrons undifferentiated except by color; ocellar setae lacking; 1 well-developed pair of intrafrontal setae inserted in front of anterior ocellus; a reclinate fronto-orbital seta and a proclinate fronto-orbital seta present, reclinate seta inserted slightly anteromediad of proclinate seta; pseudopostocellar setae present, usually well developed; both inner and outer vertical setae present; ocelli in isosceles triangle, with distance between posterior pair slightly larger than between anterior ocellus and either posterior ocellus. Antenna exerted; aristal length subequal to antennal length and bearing 4-6 dorsal rays, with basal 3-4 rays longer than apical 1-2, subequal. Eye apparently bare of microsetulae (using stereomicroscope). Face with dorsal ½ -3/4 carinate between antennae; ventral margins curved inward laterally making oral margin narrow, width subequal to narrowest distance between eyes, anterior margin shallowly emarginate; bearing 2 facial setae, the dorsal one very slightly larger, both inserted near parafacials; labella broad, fleshy, shorter than mediproboscis.

Thorax: Dorsal portion of anepisternum darker colored than medial portion, frequently concolorous with dorsal coloration of scutum, these areas separated by lighter colored band through postpronotal and notopleural areas; chaetotaxy conspicuous, setae dark colored, arranged in well-defined setal tracks as follows: acrostichal setulae in 4 rows, 2 medial rows better developed, 2 lateral rows attenuated anteriorly; dorsocentral track terminated posteriorly with larger seta; intra-alar setulae irregularly seriated; 1 postpronotal seta; 1 postalar seta; 2 scutellar setae and with sparse, scattered setulae on scutellar disc; 2 notopleural setae, insertion of posterior one elevated dorsally above anterior one; 2 anepisternal setae along posterior margin. Wing with vein R2+3 extended beyond level of crossvein dm-cu, 2nd costal section at least 1.5X longer than 3rd section.

Abdomen: Fifth tergite of male not visible from a dorsal view, telescoped within 4th.

Natural History.

Adults generally feed on nectar from different flowering-plant species and oviposit upon various kinds of decomposing organisms and excrement (Deonier, in litt.).

Discussion.

The precedent of an enlarged concept of Allotrichoma , including Pseudohecamede Hendel as a subgenus ( Mathis 1986a, 1988, 1991, 1993), is adhered to here.

For purposes of agreement between species-group names and genus-group names, the generic name Allotrichoma is neuter, not feminine.

The following is a key to the subgenera presently included in the genus.

Key to Subgenera of Allotrichoma