Stangeleon longipalpus Miller, 2008

Miller, Robert B., 2008, A new genus and species of Brachynemurini from Venezuela (Neuroptera: Myrmeleontidae), Insecta Mundi 2008 (59), pp. 1-5 : 2-5

Stangeleon longipalpus Miller , new species

Holotype male. Rio Orituco , 15 km south of Calabozo , Guarico, Venezuela, 27.II.1988, Miller and Stange ( FSCA).

Diagnosis. This straw colored species is easily identified by the elongate labial palps ( Fig. 5 ), which are only duplicated in the tribe by the North American species Scotoleon longipalpis (Hagen) and Scotoleon deflexus Adams. Since this genus has only one species, the diagnostic characters (modified tarsi, calli on the antennae, male genitalia and specialized peg-like setae on hind wing alary membrane) of the genus also serve to distinguish the species. The larva is distinctive in having an extremely wide head capsule (about twice as wide as long in dorsal view).

Holotype male. Length from head to eighth abdominal segment 32 mm. Length of fore wing 17 mm, width 4 mm at widest point; hind wing length 15 mm, width 3.5 mm at widest point.

General coloration straw colored. Head ( Fig. 2 ) with anterior area of vertex brown; middle row of vertex with a complete, distinct dark brown line extending between ocular rims; posterior row of vertex pale straw with dark setal bases. Face, petioles and labrum pale straw colored. Antenna mottled with dark brown with pale straw color on posterior side; brown calli ( Fig. 3 ) on flagellomeres 7 to 24, with rims of dark setae on flagellomeres 7 to 18. Pronotum pale straw colored with scattered dark setal bases bearing pale setae. Prescutum similar to pronotum, except for dark brown areas anteriorly, with pale areas between. Mesoscutellum pale straw colored; mesoscutum pale medially with lateral one-third dark brown above forewing base. Metascutellum pale straw colored at center with dark median line, darkened in area of hind wing base. Abdomen with tergite I straw colored with median brown spot and median black line, with light brown areas at setal bases. Tergite II straw colored with anterior lateral dark areas and median black line; tergite III straw colored with small dark median spot near posterior margin. Tergite IV straw colored with median dark brown spot at anterior and posterior margins. Tergites V, VI and VII mottled with light brown with submedian pale areas on posterior margins; sternite II with median dark Y-mark on light brown background; sternites III to IX light brown; postventral lobes straw colored with the inner ventral lateral surface with dark markings one half length of lobes. Fore coxa with two diagonal markings on outer lateral face; distal one half of fore femur marked in dark brown; fore tibia pale straw colored; mid coxa with outer lateral brown markings; mid femur with two wide brown stripes on straw colored background running length-wise on inner lateral surface; mid tibia pale straw; hind coxa mostly pale brown with some darker brown areas posteriorly; hind femur and tibia all pale straw colored. Wings straw colored with some dark brown veins and crossveins and small series of dark brown spots along subcostal area of fore wing.

Chaetotaxy as follows: head with small simple setae; pronotum with short to long pale setae; prescutum with pair of coarse white setae pointing anteriorly; mesoscutellum with several white setae on posterior margin; abdomen with long, simple light brown setae; postventral lobe and ectoproct as in Fig. 7 , with dark setae near posterior margin. Legs with long white stiff simple setae, except for black specialized setae on tarsomeres 2, 3, 4, and 5.

Structure as follows: Greatest ocular width shorter than interocular distance ( Fig. 5 ); antenna strongly clavate, with 26 flagellomeres; labial palpus elongate, distal palpomere about as long as interocular distance; pronotum about twice as long as wide; pilula axillaris moderately developed; all legs about same length; pretarsal claws, basitarsus and distal tarsomere about same length and slightly shorter than tibial spurs; abdomen much longer than wings; postventral lobe of ectoproct about eight times longer than wide; male genitalia as in Fig. 8 .

Female. Similar to male, but without calli on antennae or black peg-like setae on alary membrane; pilula axillaris absent; abdomen much longer than wings; terminalia as in Fig. 9 .

Larva. ( Fig. 10-13 ) Length of head, thorax and abdomen about 7.7 mm. Head 1.6 mm wide; abdomen 4.8 mm wide. Coloration with mandibles brown; head light brown with body straw colored with brown markings as in Fig. 10 ; ventral head capsule clear without markings. Mandibles are about as long as the head capsule viewed ventrally with the middle tooth closer to the distal tooth than the basal tooth. Distance from basal tooth to distal tooth about equal to distance of basal tooth to mandibular base. Head capsule is twice as wide as long (dorsal view) or three- fourths as long as wide (ventrally), with many dolichasters dorsally and some simple setae ventrally. Palpi are shorter than width of mandibular base. Ocelli are all black (indicating diurnal feeding) and are protected by two or three stout guard setae. Abdomen without scoli, but with raised spiracles which are about as wide as long; eighth sternite with many stout digging setae and sublateral teeth which are about as long as wide ( Fig. 13 ).

Paratypes. 2 females, l male, Rio Orituco , 15 km. south of Calabozo, Guarico, Venezuela, 27.II.1988, R . Miller and L. Stange ( FSCA) .

Biology. Stangeleon longipalpus larvae were found in an elevated area near a river. The larval habitat was small mounds of fine sand with bushes underlain with bare soil and scattered leaves. The author was drawn to the site when he saw scattered dead, crumpled ants on the surface. Shade provided by the bushes helped to keep the soil temperatures reduced. The soil was subject to periodical wetting and drying due to rain. This caused some compaction of the soil. Each larva was living in a small area of surface soil only a little larger than its body and waiting for prey such as ants to walk overhead. Blowing the soil with an aspirator removed enough sand to reveal the larvae. These larvae are slow moving when exposed, walking or digging very slowly. Only the head moves fast when grasping prey. Evidently they feed mostly during the day because the ocelli are all black, which is usually correlated to diurnal feeding. Cocoons are about 5.5 mm in diameter and are made close to the surface. Adults were collected at night and early in the morning. Like the co-existing Venezueleon guarica Stange adults, they sat on grass stems during the day and were reluctant to move or fly when disturbed, not even flying when a net was placed over them. The grassy area along the river where the adults were night collected was undulant and when individuals were seen by lantern light they were chased down. This species, unlike many antlions, flies away from light and must be chased down at night. They are not fast flyers. The capture of only three individuals, during many hours of collecting by two people, indicates the relative rarity of this species.

Figures

Figure 5-9. Stangeleon longipalpus Miller. 5) Front view of head of female. 6) Hind tarsus. 7) Posterior part of male abdomen. 8) Male genitalia. 9) Expanded ventral of female terminalia.

Figure 1-4. Stangeleon longipalpus Miller, adult male. 1) Dorsal habitus. 2) Head and pronotum. 3) Right antenna. 4) Alary membrane of hind wing showing black pegs.

Figure 10-13. Stangeleon longipalpus Miller, third instar larva. 10) Dorsal view (reared, specimen became holotype male). 11) Head with mandibles spread, dorsal view (reared, specimen became holotype male). 12) Head of cast skin in ventral view. 13) Sternite VIII of cast skin from cocoon.