Brechmorhoga praecox (Hagen 1861)

Scapanea archboldi

DESCRIPTION OF FEMALE.—Holotype.

Head (Figure 17): Labrum deep glossy purple; anteclypeus gray-brown; postclypeus shining, very pale bluish, dark centrally; frons glossy purple, pale ventrally; vertex glossy purple, apparently erect with conical projections as is typical for genus (specimen flattened).

Prothorax: Brown, with three small dark spots at base of forelobe, two lateral dark dashes on midlobe. Hind lobe suberect, rounded, with very shallow, rounded, median emargination.

Pterothorax: Obscure dark brown, with conspicuous covering of fine, dark setae, pale as follows: thin stripe on mesepisternum, expanded dorsally into distinct “L”; broad stripe, rounded below, occupying approximately rear half of mesepimeron; thin stripe, wider and rounded below, on metepisternum; broad, parallel-sided stripe, rounded below, on metepimeron.

Legs: Dark, femoral spines tapering in length, last spine (last two spines on fore femur) conspicuously longer (Figure 18). Six spines on forefemur, seven on midfemur, nine on hind femur.

Abdomen: Obscure dark brown, paler ventrally on basal segments, pale discontinuous dashes parallel to middorsal carina on sides of 3–5, extending caudally about two-thirds of 3 and 4 and less than one-third of 5. Anal appendages dark, slightly longer than 10. Vulvar lamina short, inconspicuous, rounded, with rounded central excavation. Abdomen of specimen flattened, but evidently broad, with breadth of terga of 8 and 9 suggesting slight expandability.

Venation (Figure 15): Antenodals 11½ (forewing), 8, 9 (hind wing); postnodals 7 (forewing), 8, 9 (hind wing). Forewing arculus rises one-sixth space proximal to 2nd antenodal. RPLand MPLconspicuous, one cell between these and Rs and M4 respectively. Forewing triangle and supertriangle one celled, subtriangle with three cells, discoidal field two cells wide; hind wing, triangle and supertriangle one celled. Three cell rows between A2of hind wing and wing margin.

Measurements: Abdomen 32 mm; hind wing 31 mm.

Locality: Dominica, Freshwater Lake, 16 September 1964, collected by T. J. Spilman.

This species is evidently closely related to Scapanea frontalis (Burmeister) of the Greater Antilles, although the generic diagnosis is somewhat doubtful for females. The closest genus to Scapanea is Brechmorhoga, which is represented in Grenada by one species ( B. praecox grenadensis Kirby) and in Trinidad additionally by B. nubecula (Rambur). The wing venation of the new species (Figure 15) is superficially like that of Brechmorhoga in the reduction of number of cells in the triangles and cell rows between A2and the wing margin, and number of cell rows between the RPL, MPL, and their respective principal veins. These characters do not indicate a relationship with Brechmorhoga, however, but rather a reduction of venation, largely in conjunction with reduction in size. The position of the arculus in the hind wing, which is coincident with or very close to the 2nd antenodal in Scapanea and generally more distal in Brechmorhoga, is a clue to the correct relationship. The strongest indication of affinity of the new species with the Greater Antillean genus, however, is the breadth of the abdomen, which is conspicuously greater in the new species than in either Brechmorhoga from Trinidad, or even the broader Middle American species B. rapax Calvert. Further, the femoral armature of the new species is very close in general form to that of the female of Scapanea frontalis, in which the femoral spines taper rather gradually in length proxirnally. In Brechmorhoga females the preultimate spines are subequal in length.

The new species differs from frontalis by: (1) its smaller size and relatively shorter wings (two Puerto Rican females have abdomens 33 and 32 mm, and hind wings 37 and 34/2mm); (2) its narrower ante-humeral stripes and coarser, darker, pterothoracic setae; (3) its conspicuously different facial color pattern with the more restricted pale color on the frons, the central dark color on the postclypeus, and the pale basal spots on the labrum; and (4) its reduced venation (the Puerto Rican females of frontalis (Figure 16) have two-celled triangles in the forewing and the discoidal field three cells wide; there are four cell rows between A2 and the wing margin of the hind wing; there are two cell rows for a distance of three or four cells between Rsp1 and Rs; there are 14½ or 15½ antenodals in the forewing and 10 or 11 antenodals in the hind wing).

Whether the male, when it is finally taken, will have the conspicuously clubbed abdomen of frontalis is, of course, not known. The female of frontalis, however, has somewhat widened terga on 8 and 9 which are shared with those of the new species, and I believe it is probable that the new species will be equally clubbed.

The exact habitat of the new species is not known. Again by analogy with frontalis, however, its most likely habitat is a mountain stream such as the outlet stream of Freshwater Lake.

It is with great pleasure that I name the new species for John D. Archbold, whose interests in Dominica and in natural history have combined in the patronage of a most important series of biological studies of this truly fascinating tropical island.

Brechmorhoga praecox, the slender clubskimmer, is a species of skimmer in the dragonfly family Libellulidae. It is found in Central America and South America.

The IUCN conservation status of Brechmorhoga praecox is "LC", least concern, with no immediate threat to the species' survival. The population is stable. The IUCN status was reviewed in 2017.