Leptomorphus perplexus Borkent

Borkent, Christopher J. & Wheeler, Terry A., 2012, Systematics and Phylogeny of Leptomorphus Curtis (Diptera: Mycetophilidae) 3549, Zootaxa 3549, pp. 1-117: 55-57

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Leptomorphus perplexus Borkent

new species

27. Leptomorphus perplexus Borkent   , new species

( Figures 32, 69, 79, 148, 150, 151)

DIAGNOSIS: The only extant species of Leptomorphus   with R 4 that has foretarsomere I shorter in length than the forefemur, the lateral ocelli placed less than their own diameter from the eye margin ( Fig. 79), and no dark wing spot ( Fig. 69).

This species is most easily confused with either the light form of L. nebulosus   ( Fig. 27) or L. magnificus   ( Fig. 21). It can be distinguished from the former by the lack of any dark markings on the scutum and the monochromatic antennae ( Fig. 32). It differs from the latter species by the yellow head, the sinusoidal R 5 wing vein ( Fig. 69) and the placement of the lateral ocelli approximately their own diameter away from the eye margin and the median ocellus ( Fig. 79).

DESCRIPTION: Female. ( Fig. 32) Head: ( Fig. 79) yellow-orange, circular in anterior view. Antenna brown; scape yellow, with yellow setae on entire surface except basal 1/4, anterobasal patch of setulae present; pedicel yellow, with 1–2 large bristles, few setae on apicodorsal margin, patch of fine setae apicoventrally; flagellomere 1 with tapered base yellow remainder brown; flagellomere 6 1.3X as long as broad. Clypeus yellow, circular, strongly protruding; bristles on clypeus light brown, both strong, smaller bristles on entire surface, all directed ventrally, clypeus 2X as long as face. Face yellow; shape a slightly wider than tall triangle, with fine bristles covering face. Frons yellow; with many bristles covering ventral half, frontal furrow running 1/10–1/4 distance from dorsal margin towards ventral margin, frontal cleft faint running to lateral ocellus. Palpus yellow; segment 1 hidden behind eye, segments increasing in length, segment 5 1.5X length of segment 4 with even width from base to apex, segment 3 appears to have large lateral patch of fine yellow setae not clearly delimited and interspersed with dark setae. Labellum yellow. Eye with many long inter-ommatidial setulae (in most inter-ommatidial junctions) on all but medial margin. Occiput yellow with appressed, anteriorly directed setae. Ocelli in a straight line, space between ocelli 1–1.5X diameter of laterals, lateral ocelli 0.5X their own diameter from eye margin, ocellar triangle brown ring around each ocelli but not overlapping other ocelli. Thorax: Length 1.82 mm (1.72–1.89 mm, n = 4). Yellow. Scutum yellow; surface of scutum covered with small setae; acrostichal setae vaguely present; dorsocentral setae probably present but not clearly distinguishable from other setae; multiple rows of lateral setae present; patch of setae on scutum at wing base present. Scutellum yellow; with 8–10 large bristles and many small bristles. Prescutum yellow. Mediotergite yellow with 22–28 bristles on posterior third, absent. Laterotergite yellow; anterior margin of laterotergite not reaching katepisternum. Anepimeron yellow. Anepisternum yellow. Katepisternum yellow. Antepronotum and proepisternum yellow. Margin of anterior and posterior spiracles yellow with yellow trichia. Metepisternum yellow. Anapleural suture straight and clear. Halter yellow. Legs: principally yellow; extreme anteroapical corner light brown on hind femur, on other femora yellow. Midfemur without apical spine-like process. Tibia with covering of brown macrotrichia, tibial spurs yellow to light brown, foretibial spur length 2.5X apical thickness of foretibia, shortest midtibial spur subequal to length of longest, longest midtibial spur 5X apical thickness of midtibia, shortest hind tibial spur 0.85X length of longest, longest hind tibial spur 5X apical thickness of hind tibia. Foreleg first tarsomere 0.9X length of foretibia. Wing ( Fig. 69): Length 6.6 mm (6.0– 6.9 mm, n = 4). Hyaline; apical macula absent; medial macula absent. Macrotrichia in all cells. Setae on basal posterior margin of wing (along base of cell a) alternating long, short. Calypter with group of macrotrichia. Vein sc-r present, apical end joining R 1 at least 3X its own length after origin of Rs. R 4 present. R 5 slightly sinusoidal. M 1 reaching apex at same level as R 5, apices of M veins clearly reaching wing margin. M 4 -CuA fork arising well before origin of r-m. A 2 present. Abdomen: Tergites principally yellow, T1 light brown. Cercus yellow.

Male. Unknown.

Immatures. Unknown.

BIOLOGY: Unknown.

DISTRIBUTION: California, USA (Tuolumne Co., Amador Co. ) ( Fig. 148), 750 masl   .

DISCUSSION: Even though this species exhibits a number of plesiomorphic characteristics (i.e. ocelli not forming an ocellar triangle, inter-ommatidial setulae covering most of eye, acrostichal setae present), it fits within the current limits of the genus. This placement should be confirmed when male specimens are found. It should be noted that the cell created by R 4 is longer than that found in other Leptomorphus species.   The sinusoidal shape of R 5 is also unique within Leptomorphus   , though this condition is seen in other Sciophilini   genera such as Neuratelia   and Polylepta Winnertz.  

ETYMOLOGY: The species name refers to the confounding thought process that went into determining that this species was placed within Leptomorphus   , due to both the number of plesiomorphic characters and lack of male material.

MATERIAL EXAMINED: Holotype: here designated, adult female, pinned, labelled “[ USA] CAL.: Tuolumne Co. / Basin Creek Cmpgd./ 31.v.1963 / P.H. Arnaud, Jr.; HOLOTYPE ♀ / Leptomorphus perplexus   / Borkent, new species / Det. C.J. Borkent 2012” [ USNM]  

Paratypes: labelled as for holotype (3♀, USNM). USA, Amador Co., Indian Grinding Rock State Park , dry wash nr. S. Nature trail. MT#2, 38°25’ N, 120°8’ W, 715masl, 24.v–10.vi.2007 GoogleMaps   , 07LOT096, P. Kerr & M. Hauser / 07Y771 (1♀, CSCA)   .


Smithsonian Institution, National Museum of Natural History


California State Collection of Arthropods