Erpetogomphus molossus, Bailowitz, Richard, Danforth, Doug & Upson, Sandy, 2013

Bailowitz, Richard, Danforth, Doug & Upson, Sandy, 2013, Erpetogomphus molossus, a new species from Sonora, Mexico (Odonata: Anisoptera: Gomphidae), Zootaxa 3734 (5), pp. 559-570 : 559-567

Erpetogomphus molossus , new species

Etymology. The name molossus is intended both to continue the tradition in the naming of new species of Erpetogomphus after snakes and to refer to this particular new species’ most conspicuous field mark: its largely black, though ringed, abdomen. The small range of Erpetogomphus molossus is well within the much larger range of its namesake, Crotalus molossus , the black-tailed rattlesnake. The common name Black-tailed Ringtail is suggested.

Specimens examined. 3♂ 3♀. Holotype male from Rancho Trigo Colón, 10 km S Hwy 16, Km 296, Yécora Municipio, Sonora, Mexico, 1385 m (N 28°18.593’, W 108°47.503’; date 14-IX-08; leg. R. Bailowitz, D. Danforth & S. Upson. Allotype female from same locality by same collectors, 16-IX-04. Paratypes All from same locality and collectors, 1♂ 4-IX-05, and 1♀ 16-IX-04. Holotype and allotype in collection of Instituto Biologico de la Universidad Nacional Autónoma de México, Mexico City. Paratypes in Hasbrouck Insect Collection, Arizona State University, Tempe, Arizona.

Description. Male holotype ( Figs. 3–7 ). Head. Face predominantly light turquoise in life; mandibles pale on proximal surfaces near points of articulation, grading through reddish brown to blackened tips while narrowing distally; maxillae pale throughout except tips which are darkened slightly to light brown; posterior to each lateral ocellus, a darkened tubercle with roughly a dozen long setae; vertex dark becoming paler posterior to postocellar turbercles; occiput pale, angled upward and bordered with black on front, rear and both ends; crest erect, black on each outer quarter, pale on inner half; posterior margin bilaterally sinuate, with tufts of long setae its full length; setae matte yellow apically, dark brown basally.

Prothorax. Anterior half of anterior lobe pale, arched upward and posteriad in middle two quarters; posterior half of lobe darkened to lateral extremes; dark area curving forward to include outer two quarters of lobe’s anterior half; proceeding laterad, outer quarters first excavate, then secondarily arched; anterior margin of middle lobe folded forward and down; middle lobe itself divided into pale, bluntly pointed halves meeting mesally; lateral extremes of lobe defined by a shallow ridge angling posterolaterad, then directly laterad. Outside these ridges, lobe pale dorsally, medium brown anteriad; posterior lobe gracefully arched and pale darkening through reddish brown ultimately to black on posterior margin; margin thickened, rolled and setose.

Pterothorax. Raised middorsal thoracic carina turquoise (in life) becoming dark brown at middorsal prominence or anterior extreme of antealar crest; middorsal carina (postmortem) bordered laterally by respective halves of dark brown middorsal stripe; sides of anterior surface of pterothorax marked by very thick, inverted “7s” of bright turquoise (yellow, postmortem) in lower frontal area; crossbars of “7s” extended to include collar; dark brown antehumeral and humeral stripes fused at bottom, top and 3/4 point leaving between them an inverted turquoise “exclamation mark;” lateral area of thorax uniformly bright green except for faint and narrow brown stripe running along metapleural suture.

Legs. Coxae and trochanters variably mottled between straw-colored and drab green; femora pale proximally, outer surfaces grading through reddish brown to black distally; tibiae and tarsi black.

Wings. Hyaline with trace of amber at extreme bases; costal veins pale yellowish out to proximal point of pterostigmata; pterostigmata dark brown dorsally, medium brown ventrally; remainder of venation black; Left side antenodal crossveins number as follows: LFW 13, LHW 12. In LFW, first and fifth antenodal crossveins thickened; in LHW, first and sixth crosssveins thickened; in each wing, reinforcement gained from thickening enhanced by costal veins’ precise alignment with similarly thickened subcostal veins behind them; postnodal crossveins number: LFW 10, LHW 10; beyond slanted braceveins, pterostigmata subtended by 3.5 and 4.3 cells in LFW and LHW, respectively. In LFW, 7 paranal cells, with 3 supplementary marginal cells behind them; second anal interspace of LHW has single full-width cell next to anal vein. Posterior to this, second row has 2 cells; anal triangle of LHW shows common male Erpetogomphus complement of 3 large cells arced around single smaller cell near middle of triangle’s mesal margin.

Abdomen. Dark brown to black in ground color, with pale turquoise dorsal stripe (becoming matte yellow postmortem); stripe partial on S1, full on S2, thinner and with progressively greater interruptions on S3–6; S7 broadly banded with off white in basal 2/3; S8 with obscure, pale, basal mark on dorsum: margins of auricles on S2 show line of small, regularly spaced black denticles; S1–3 show pale ventrolateral areas; basal annuli of S4–6 confluent with pale dorsal stripe and, in lateral to ventrolateral areas, extended posteriad in vague boomerang shape; in same segments, obscure, slightly pale streaks aligned along, and just above, ventrolateral carina; S7 pale in basal 2/3, black in apical 1/3; supplementary transverse carina black laterally conjoined with semicircular, black lateral spot in basal quarter; S8–10 black dorsally with incomplete, red-brown basal rings dorsally and dorsolaterally; S8–10 also show irregular, pale, basolateral patches, those of S10 more strongly reddish brown; a further reddish brown dorso-apical patch present on S10; sternites of S3–6 and basal 3/4 of S7 black.

Hamules. Anterior hamule light brown at base turning black and terminating in robust C-shaped structure open posteriad and comprising more than half total length of hamule; proximal branch of “C” thickly blunted, even squared off; middle section thick, shallowly curved, tapering distally to form thin, sickle-shaped, almost fully recurved (180°) distal branch of “C”. Posterior hamule thick, pale, setose and half again as long as anterior hamule; at base, initially projecting away from abdomen, then angling posteriad and tapering to bluntly rounded, broadly blackened tip armed with prominent tooth originating at and recurving forward from point clearly posterior to true apex of hamule.

Penis (vesica spermalis). Terminal segment of penis lacks prepuce. Paratypes each with small, lateral lobes bearing 5–7 minute denticles along dorsal margins; in holotype, lobe is collapsed at base leaving number of denticles obscured; membranous hood broadly excavate posteriad, fully exposing subcuticular membrane and much of pebbled tissue at base; cornua wide, widely separated and divergent, terminating in rounded, expanded, scoop-like tips flared incipiently outward; avisible swelling along mesal margin and a more pronounced swelling along lateral margin; length of segment 4, including cornua, twice width of segment.

Terminal appendages. Cerci off-white to yellowish; in lateral view, narrowed and slightly arched in middle, but not angulate; beyond middle, cerci widen, culminating in rounded, bulbous tips; in posterior view, tips slant diagonally down and in and are cupped, not bulbous, on inner surfaces; cercus with prominent, decumbent, darktipped and blunt, basoventral process; epiproct dark and slightly elevated dorsally at 1/3 point, reaching to half length of cercus; despite being upturned to roughly 100°, epiproct truncated, falling well short of intersecting cercus; apical margin of each tip shallowly rounded and armed just below lateral corner with prominent, black tooth projecting forward.

Measurements (in mm). Total length 47, abdomen 35, FW 33, HW 31.

Female allotype ( Figs. 8–11 ). Head. Face muted turquoise blue-green with darkened, fan-shaped area centered upon and radiating forward from postfrons base. Between postfrons base and vertex a pronounced trough crosses head in a straight line between compound eyes; path of trough tangential to rear of antenna bases and to front of median ocellus, deepening to noticeable pits anterolateral to median ocellus; posterior to lateral ocelli, lowlying but well defined tubercles present; posterior surface of vertex mostly smooth, though broadly and shallowly recessed into triangular, basin-like shapes; on incline nearing occiput, vertex strongly wrinkled across entire width. Occiput greatly reduced from dimensions typical of male, inclined to near vertical and best seen in anterior view; sinuously curved, arcing forward and inward from behind eye and becoming temporarily visible, from above, at innermost point of eye; at its forward extreme, occiput arcs to rear becoming clearly convex; crest elevated, light yellow mesally, dark laterally, fringed with golden setae; postocciput large, drab yellow.

Thorax, legs, and wings. Similar to male.

Abdomen. Mostly black with thin, pale, blue dorsal stripe through S3, rusty through anterior half of S7; S3–7 with pale, basal annuli, incomplete dorsally, thin but thickening above ventrolateral carina and elongated to rear as a boomerang shape abutting transverse supplementary carina; S7 similar, yet transitional, with regular and entire apical annulus rusty in color; S8 and S9 also with rusty apical annuli, but lacking pale basal annuli; ventrolateral area of each abdominal segment with pale markings posterior to transverse lateral carina; these vary from thin streaks to thickened, mottled patches and, in terminal segments, show rusty tinges; appendages also rusty; cerci thick at bases, tapering straightly and evenly to darkened, acuminate tips; paraproct robust. In ventral view, sternite of S1 similar in olive-gray color to lateral areas of tergum above; from halfway point of S2 through full length of S7, sternites almost entirely black, hastate with narrow ends pointed to rear; sternite of S8 black only in apical half; those of S9 and S10 partially darkened, though not black.

Subgenital plate. Mesal margins of bifid subgenital plate fused in anterior 50%, then diverging at ±100° to each other, terminating at darkened, slightly thickened posteromesal corners armed with a tight cluster of minute denticles; median cleft, as measured between darkened corners, equals approximately 40% of total width of plate; a small, shallow notch immediately outside each corner; outer margins of plate curve gently, but irregularly, forward approaching their lateral extremes; surfaces and posterior margins of plate slightly wavy and lying anterior to a thickened, raised and costate, roughly Y-shaped postlamellar ridge.

Measurements. Total length 48 mm, abdomen 35 mm, FW 37 mm, HW 35 mm.

Variation. Measurements of holotype and two additional males as follows: total length 47–48 mm; abdomen 36–37 mm; FW 32–33 mm; HW 31–32 mm.

Flavescence found in wings of both sexes, generally faint, often absent altogether. Two cells usually present in second row of second anal interspace of HW, one cell in some individuals. Venation pattern within anal triangle inconsistent; 3 larger cells usually in an arc around smaller cell on mesal margin; some individuals lack smaller cell in one or both HW.

Male epiproct tips also variable; tips of holotype male asymmetrically rounded in posterior view; tips of other individuals slightly angulate and varying between nearly smooth and irregularly and minutely jagged, as though gnawed off; 5–7 denticles on margin of lateral lobes of penis (6 most common); 5–9 denticles along margin of auricle.

Females examined show little variation, beyond extent of darkening on posteromesal corners of subgenital plate; total length 48–49 mm.

Figures

FIGURE 3. Head, thorax and basal abdominal segments of holotype male.

FIGURE 8. Head of allotype female, in frontal view.