Rhaphiomidas pachyrhynchus, Rogers, Rick & Van, Matthew H., 2007

Rogers, Rick & Van, Matthew H., 2007, Two new species of Rhaphiomidas (Diptera: Mydidae), Zootaxa 1664, pp. 61-68 : 62-64

Rhaphiomidas pachyrhynchus sp. nov.

Diagnosis: This medium sized species is easily recognized by the very thick (> 1mm) proboscis and by the pair of bullae on the second abdominal tergite, which is unique in the genus. The front tibia and tarsi are densely clothed with long golden pile. The basal half of the hemitergites exterior surface is densely clothed with long orange pile, whereas the distal half is unclothed. The terminalia are heart-shaped with subdorsal, longitudinal carina extending from the base to the middle of each hemitergite. The aedeagus is curved strongly upward.

Description of holotype: Male ( Fig. 1 a): Head: vertex, frons and face dark gray pruinose; posterior surface of head lighter gray pruinose; dense pale yellow pile on all surfaces except vertex which has numerous dark brown to black hairs. Antennae: scape dark gray, slightly shining, ventral surface with dense pale yellow pile, dorsal surface with a small number of white macrochaetae; pedicel, dark gray, pruinose, reddish brown at apex, ventral surface with tuft of pale yellow macrochaetae, reddish near bases, dorsal surface with a small number of pale yellow macrochaetae, also red near bases; segment three, dull black, reddish brown near base. Proboscis: short, about 8 mm (twice the length of the antennae), and thick, almost 1 mm at widest part near the base. Thorax: humeral callosities not deeply incised posteriorly. Mesonotum cinereous, with a slight olivaceous tint, weakly shining, without markings, densely covered with straw-colored pile, postalar callosities with six long, pale yellow macrochaetae on each side, above a tuft of pale yellow pile. Scutellum deeply divided from posterior mesonotal margin, similar in color and pilosity to mesonotum. Lateral thoracic sclerites dark gray, weakly shining, becoming reddish brown around the postnotal conical swellings and metathoracic spiracles; lateral thoracic sclerites with seven dense tufts of straw to white pile; postnotal conical swellings large and robust, weakly shining, with very short gray pile; halters with stalk reddish brown, club orange in color. Wings with costal vein black pilose in basal third, the remaining portion short, black pilose. Legs: coxae dark gray, weakly shining; fore and mid coxa densely clothed with pale yellow pile; hind coxa with three tufts of pale yellow pile, and a considerable amount of black pile. Trochanters piceous, nitid; fore trochanter densely pale yellow pilose, mid trochanter with small amount of pale yellow pile, mostly dark brown pilose, hind trochanter dark brown pilose, with four black macrochaetae. Femora piceous, nitid, weakly wrinkled, shallowly grooved longitudinally along most of the length, apical area of fore and mid femur shining amber; fore femur with small amount of black hairs basally, entire length densely covered with pale yellow sinuous pile, inside surface with seven to nine light brown macrochaetae arranged in a zigzag formation; mid femur with dense pale yellow sinuous pile dorsally, moderately dense shorter black hairs laterally and ventrally, three to four light brown macrochaetae laterally on apical portion, double row of four to five black macrochaetae ventrally; hind femur with light brown pile turning pale yellow apically on dorsal and lateral surfaces, ventral surface with mix of short and long black hairs basally, with apical third long sinuous pale yellow; pile, with double row of ten light brown to black macrochaetae. Fore tibia weakly shining with a scaly surface, gray basally, turning orange apically, dorsal surface with dense pale yellow pile, ventral surface with longer sinuous pile, with a small number of pale yellow macrochaetae; mid tibia same as above, but with pale yellow pile shorter, ventral surface with a few black hairs, also with six short black spines; hind tibia dark brown, same surface texture as above, short dense pale yellow pile anteriorly, long, dense, sinuous pile laterally and ventrally, about fifteen pale yellow macrochaetae on all surfaces except the inside which has a double row of short black spines. Fore tarsus pale orange, dorsal surface with short porrect pale yellow pile, lateral and ventral surfaces with long reclinate pale yellow pile, extending to fifth tarsal segment, a variable number of small pale yellow macrochaetae are present; mid tarsus pale orange with much shorter pale yellow porrect pile, and a triple row of short light to dark brown spines; hind tarsus pale orange, dorsally with short porrect pale yellow pile, ventral surface with long proclinate hairs on first tarsal segment, a variable number of rather small pale yellow macrochaetae are arranged in a zigzag formation on all segments, and a double row of eleven to thirteen short black spines are on the interior ventral surface of the first segment; pulvilli and claws of all tarsi pale orange, pulvilli large, greatly expanded apically. Abdomen: all tergites black, highly polished, with narrow apical borders of reddish brown on tergites II and III, tergite II with a pair of reddish brown oval bulla ( Fig. 1 d), one on each side near the apical portion of the tergite; tergite I with pale yellow erect sinuous pile, denser on the sides; tergite II densely covered with pale yellow sinuous pile, proclinate basally, erect medially, and reclinate apically; tergite III with pale yellow sinuous pile, erect except for fringe of pile slightly above apical border, which is reclinate; tergite IV same as tergite III; remaining tergites the same except for the lack of an apical fringe of pile; sternites mostly black, highly polished, pilosity the same as tergites, sternite II with irregular orange spots (one on each side) laterally; sternite III with oval spots of orange basally and laterally; sternite IV with small basal orange spots laterally; remaining sternites black, with increasingly dense orange pile. Terminalia: hemitergites heart-shaped ( Fig. 1 b), black, weakly shining, reddish brown border on lower margin, continuing up almost to apex; inside surfaces of hemitergites with prominent subdorsal carina, which extend from the base to the middle of each hemitergite; dense orange pile basally, going across the hemitergite diagonally to lower margin, but not extending to apex; short black hairs are present on the exposed portion of the hemitergites. Aedeagus light reddish brown, base laterally compressed, the rest of the length extremely recurved ( Fig. 1 c). Gonostyles about half the length of the hemitergites, slender, shining reddish brown, with orange sinuous pile, basal projections ear-shaped, small, about one fourth the length of the gonostyles.

Length overall: 25 mm, mesonotal width 6 mm.

Female: Unknown.

Holotype: (male) Mexico, Nuevo Leon, 60 miles south of San Roberto junction, elevation 5800 feet, September 26, 1967, Reginald E. and Elizabeth M. Painter, collectors (Deposited USNM)

Etymology: pachy (Greek) = thick), rhynchos (Greek) = snout), the name referring to the thickness of the proboscis, thicker than any other known species of this genus.

Ecology: Unknown.

Relationships: Rhaphiomidas pachyrhynchus sp. nov. is a very distinct species, apparently not closely related to other species in the genus. It is the only species in the genus to possess bullae. This character separates it from all other species in the genus. Other characters that are used to identify it are the hemitergites, which are distinctively covered in dense orange pile basally and are bare in the distal half. The aedeagus is also unique in the genus for being extremely recurved. The proboscis is also thicker compared to other species in the genus. The relationship to other species in Rhaphiomidas is unclear and further investigation is needed.

Rhaphiomidas pachyrhynchus does not easily key out in the key of Cazier (1985). The distinctiveness of some characters does however allow for it to be easily separated. A new couplet in the key of Cazier (1985) would be as follows.

1. Bullae clearly present on abdominal tergite II ......................................................... pachyrhynchus sp. nov. Bullae not clearly present on abdominal tergite II...................................................................................... 2

Figures

FIGURE 1. Rhaphiomidas pachyrhynchus sp. nov., (a) male, lateral habitus (b) hemitergites, dorsal view (c) aedeagus, lateral view (d) abdominal tergite II with bullae, dorsal view.