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

Rogers, Rick & Van, Matthew H., 2007, Two new species of Rhaphiomidas (Diptera: Mydidae), Zootaxa 1664, pp. 61-68 : 64-67

Rhaphiomidas moapa sp. nov.

DIAGNOSIS: This species is separated by narrow abdominal tergites primarily gray with slight bluish reflections. Each tergite is bordered apically with a light yellow vitta. The hemitergites inner surface is deeply concave without spines or carinae and non-overlapping apices. The combination of the narrow gray abdominal tergites and non-overlapping hemitergites distinguish this species from all other Rhaphiomidas .

Description of holotype: Male ( Fig. 2 a–b): Head: vertex, frons and face entirely pruinose, moderately covered with long white pile. Compound eyes separated from the lateral ocelli on vertex by about the width of a lateral ocellus; antennae with segments one and two gray pruinose, segment three orange; proboscis long, up to 9 mm in length. Thorax: humeral callosities deeply incised posteriorly, surface brownish gray pruinose, sparsely white pilose and macrochaetose; mesonotum with two medium longitudinal dark vittae and two lateral vittae one on each side; scutellum deeply acutely delimited from posterior mesonotal margin, sparsely clothed with white setae; mesopleural sclerites gray pruinose, sparse white pilosity around basalare and dorsocaudal angle, postnotal conical swelling gradually constricted to acute apical point, halteres pale orange. Wings: costal vein gold micro-pilose in basal portion, all veins brownish-orange in color. Legs: fore and mid legs see Fig. 2 b; hind leg with femur slightly swollen, tibia ventral surface with double row of short black spines, first tarsal segment elongate longer than combined length of remaining segments, ventral surface covered with long re-curved pile and double row of short black spines, dorsal and lateral surfaces moderately densely covered with small gold setae. Remaining tarsal segments luteous with gold macrochaetae. Abdomen: All tergites primarily gray, weakly pruinose, each narrowly bordered apically with pale yellow transverse bands, moderately densely clothed with long semierect white pile, longer laterally, sternites as in tergites in color and pilosity. Terminalia: narrow, heart-shaped, sutural margins not overlapping, hemitergites ( Fig. 3 a), shining black medially, narrowly bordered apically and ventrally with reddish-brown, surface moderately clothed with white setae becoming longer laterally, gonostyles slender, clavate apically, extending three quarters the length of hemitergites, reddish brown with swollen lobes near base and swollen apical ends luteous, ventral surfaces densely covered with white pile, aedeagus small, light yellow in color ( Fig. 3 b). Length 26mm, Mesonotal width 6.5mm

Female: similar to male, except for the following; compound eyes separated from lateral ocelli on vertex by more than the width of a lateral ocelli. Fore and mid tibia and tarsi light brownish orange, femora dark gray, hind legs dark gray. Last three abdominal segments with small retorse setae; terminalia with acanthophorites small and reddish-brown.

Holotype: (male) USA, Nevada, Clark County, wash <0.1mi. south of Overton, HWY 169, May 24, 1998, 36°30’34”N 114°25’33”W, 1240 ft., R. Rogers ( LACM)

Paratypes: (2 males, 1 female), USA, Nevada, Clark County, wash <0.1mi. south of Overton, HWY 169, May 24, 2005, 36°30’34”N 114°25’33”W, 1240 ft., M. Van Dam ( EMEC)

(1 female) USA, Nevada, Clark County, wash <0.1mi. south of Overton, HWY 169, May 24, 1998, 36°30’34”N 114°25’33”W, 1240 ft., R. Rogers ( LACM)

(5 males, 7 females) USA, Nevada, Clark County, wash <0.1mi. south of Overton, HWY 169, May 24, 1998, 36°30’34”N 114°25’33”W, 1240 ft., R. Rogers (personal collection Rick Rogers)

(1 female) USA, Nevada, Clark County, wash <0.1mi. south of Overton, HWY 169, May 28, 1998, 36°30’34”N 114°25’33”W, 1240 ft., Rick Rogers (personal collection Rick Rogers)

(1 male, 1 female) USA, Nevada, Clark County, wash <0.1mi. south of Overton, HWY 169, May 24, 2005, 36°30’34”N 114°25’33”W, 1240 ft., Rick Rogers (personal collection Rick Rogers)

Etymology: This species is named in honor of the Moapa Tribe of Native Americans.

Ecology: Rhaphiomidas moapa sp. nov. is only known from the type location. It has not been recorded in any other washes in the area and may be highly restricted. Despite surveying of the area by several collectors (Rogers, Ballmer, Osborne, Van Dam and others) no other locations have been found. R. moapa is absent in years of drought and is only active in years of moderate or heavy precipitation. This species has only been collected in mid to late May. R. moapa prefers to fly along the sides of a wash where fine sand is deposited in small dunes. Several specimens were collected in open dune areas removed from the wash (Osborne per. obs). Observed nectar sources are Eriastrum sp., Chilopsis linearis (Cav.) Sweet and Petalonyx parryi A. Gray. An observed predator of R. moapa is Proctocanthus nearno Martin ( Asilidae ). The distribution of R. moapa is sympatric with R. auratus Cazier , they also have been seen feeding out of the same flowers. Four empty pupal cases (all female) were recovered from the sand dune area at the northwest side of the wash. As usual for the genus, the cases were found by looking for holes in the harder top crust of the sand. All were near the bases of Ambrosia dumosa (A. Gray) plants. The pupa is distinguished from R. auratus by the much shorter proboscis sheath.

Relationships: Rhaphiomidas moapa is another distinctive species that does not have any clear similarities with other species in the genus. The overall body shape and coloration is similar to that of R. parkeri Cazier. However the hemitergites are overlapping in R. parkeri and are heart shaped in R. moapa . Also on the ventral surface of all femora, tibiae and first tarsi possesses a double row of short dark spines. The spines are most pronounced in the hind legs. This character is absent in the legs R. parkeri . Another species R. moapa resembles is R. brevirostris Cazier. The two can be easily differentiated because R. moapa has non-overlapping hemitergites. Also the third antennal segment is elongate with the widest part medially, in R. brevirostris the widest part is anterior to the middle. Further study is needed to understand the relationship that R. moapa has in the genus.

This species keys out with R. trochilus in the key of Cazier (1985). An additional couplet for this species would be as follows.

14. Abdominal tergites gray, narrowly bordered apically with pale yellow transverse bands .... moapa sp. nov. Abdominal tergites black or dark brown in the basal three-quarters to two-thirds bordered along apical margin with pale yellow, or abdominal tergites orange............................................................................. 15 15. Abdominal tergites black or dark brown in basal three-quarters to two-thirds, narrowly bordered along apical margin of each segment with pale yellow or cream color; terminalia elongate, narrow ...... trochilus Abdominal tergites orange with at most small medial dark isolated spots on segments three and four; terminalia robust, wide ..................................................................................................................... nigricaudis

Figures

FIGURE 2. Rhaphiomidas moapa sp. nov., (a) male, dorsal habitus (b) male, lateral habitus.

FIGURE 3. Rhaphiomidas moapa sp. nov., (a) hemitergites, dorsal view (b) aedeagus, lateral view.