Argia rudolphi Garrison & von Ellenrieder, n. sp.

Figs. 19 (head, thorax, S1– 4 ♂); 43 (head, thorax, S1– 4 ♀); 68 (S7– 10 ♂); 92 (S7– 10 ♀); 113 (mesostigmal plates ♀); 154 (appendages ♂); 168 (map); Table 2 (measurements).

Etymology. Named rudolphi (Latinized name) in honor of our colleague Rainer Rudolph, in recognition for his generous support of the International Dragonfly Fund, which has helped further the knowledge of Odonata worldwide over the past twenty years.

Specimens examined. 18 ♂, 5 ♀. Types. Holotype ♂: MEXICO, Puebla State, Zihuateutla, Sierra de Huauchinango, La Unión, in drainage area (20°14'25'' N, 97°53'38'' W, 596 m), 21 v 1987, R. Novelo & A. Gomez leg. [CSCA] . Paratypes: MEXICO, Hidalgo State: 6 ♂, 3 ♀, stream with cascade 7 km N of Tlanchinol (21°3'5'' N, 98°40'4'' W, 1,300 m), 21 vii 1992, G. Harp leg. [RWG] ; 2 ♂, same data but 22–23 vii 1992, TWD leg. [RWG]; Puebla State: 1 ♂, Zihuateutla, Sierra de Huauchinango, km 3 road to. La Unión, Zona Cafetalera in drainage area (20°15'31'' N, 97°52'5'' W, 570 m), 23 vii 1987, R. Novelo leg. [CSCA] ; 4 ♂, same data but [RWG]; 3 ♂, 1 ♀ (one pair in tandem), same data as holotype [RWG]; Veracruz State: 1 ♂, 1 ♀ (in tandem, female ovipositing), El Muro, km 14 on road 131 Tlapacoyan-Altotonga (19°52'41'' N, 97°13'41'' W, 1,100 m), 15 vii 2000, R. Novelo leg. [RWG].

A medium-sized largely violaceous-blue species (Figs. 19, 68, based on well-preserved material) with approximate cerci (Fig. 154) the male of which is similar to A. anceps (Figs. 20; 69; 181), A. fissa (Figs. 21; 70; 183) and A. westfalli (Figs. 22, 23, 71, 72).

Description of male holotype. Head (Fig. 19): Labium pale except for small black medial spot at base; ante- and postclypeus, antefrons, base of mandibles, anterior half of scape and genae pale, remainder of head black with violaceous postocular spots confluent with eyes, incomplete pale occipital bar and small pale spot anterolateral to lateral ocellus; posterior half of scape and remainder of antennae black, rear of head washed with black, especially medially, margin bordering eye margin pale.

Prothorax black with following areas pale: obscure lateral spot on anterior lobe, dorsolateral spot on middle lobe, lateral 0.30 of posterior margin of pronotum, propleuron except for notopleural suture. Pale areas of pterothorax violaceous blue, with black middorsal stripe about as wide as pale antehumeral stripe, the latter slightly narrowing dorsally; anterior half of mesinfraepisternum black, continuous with broad humeral stripe at base, then narrowing at basal fifth along mesopleural suture, then abruptly forming a thin hairline at 0.50 before expanding again at mesopleural fossa and connecting narrowly below antealar crest with middorsal stripe above; metapleural suture with a narrow black stripe separating paler areas on side of thorax (Fig. 19). Wings hyaline with venation black; pterostigma dark brown, surmounting 2 cells in both Fw and 2 cells in left Hw [distal 0.80 of right Hw missing]; postnodals Fw 18/19, left Hw 16; postquadrangular cells Fw 4/4, left Hw 3; RP2 at Fw 8/8, left Hw 6. Coxae and trochanters pale medially washed with brown; extensor surfaces of tibiae pale, remainder of legs and armature black.

Abdomen (Figs. 19, 68) mostly violaceous blue; S1 pale with narrow black basal ring expanding dorsally to form a connected black spot occupying basal 0.50; S2 pale above with an incomplete black lateral stripe widening posteriorly and ending at distal 0.30, this stripe connected to obscure black spot below thus isolating pale areas anteriorly and posteriorly, genital lobe not strongly produced, apical annulus black; S3 pale with an narrow lateral black stripe, apical 0.20 including annulus black except for small isolated transverse spot before annulus; S4 similar to S3 but with remnant of postbasal streak; S5 similar but postbasal streak more extensive with vestigial line connecting to apical black; S6 with postbasal black confluent with apical black thus forming a broad ventral stripe; S7 black except for narrow pale ring with a broad triangular extension middorsally ending at basal 0.20; S8– 10 pale dorsolaterally and black ventrally; torus pale, cerci black; dorsal portion of paraprocts pale, ventrally black.

Genital ligula (Fig. 137) similar to A. elongata (as in Fig. 132) but tip narrower. Lateral lobes appressed to lateral margin of distal segment

Torus large, transversely triangular, swollen ventrally, occupying ventral half of torifer and overlapping recessed bilobed epiproct (Fig. 154 c); narrow area around epiproct and extreme base of same black; cercus roughly quadrate in dorsal view with outer margin about 1.5 times as long as inner margin (Fig. 154 c); in mediodorsal view upper surface slightly concave with a broadly based tooth at basal 0.20 (Fig. 154 a, d); in lateral view, narrowly triangular, subequal to length of paraproct (Fig. 154 b); paraproct slightly bilobed, its ventral branch much smaller than longer, anteriorly directed, bluntly triangular dorsal branch, its tip, viewed mediodorsally (Fig. 154 a), directed medially.

Dimensions. Hw 21.5, abdomen 30, total length 37.5.

Description of female paratype (Mexico: Veracruz State, El Muro, km 14 on road 131 Tlapacoyan- Altotonga). Similar to male but pale color light blue. Head (Fig. 43) as in male but with a black basal spot mediolaterally on labrum and postocular spots larger and confluent with eye, prothorax as in male but black areas less extensive, pterothorax with humeral stripe narrower and more deeply forked; S1 as in male; S2 with dorsal oval spot at basal 0.60, apically and laterally with black interrupted below by a pale lateral stripe narrowed at apical 0.30, pale lateral stripe bordered below by a black stripe; S3 dorsally pale with apical 0.30 black, the latter with a ventral offshoot of black along ventral margin and expanding at basal 0.10 and almost connecting with an elongate postbasal streak, which is at first broad but narrows to a thin line just connecting with apical black; S4–5 similar to S3 but black more extensive, isolating a pale midlateral stripe; dorsal blue also reduced, especially apically, but with an incomplete pale basal ring; S6–7 black with an incomplete pale basal ring; S8 blue dorsally, black at basal 0.20 and laterally; S9 blue dorsally with a black dorsolateral spot at basal 0.50 and connected to lateral stripe below; S10 blue dorsally, black laterally; appendages and ovipositor black.

Mesostigmal lobe forming a broad oval (Fig. 113 a, b), about twice as wide as high, occupying medial 0.60 of posterior margin of mesostigmal plate (Fig. 113 c), medial margin thickened with a slightly recurved margin (Fig. 113 d, e), and slightly overlying fork of middorsal carina; distance between mesostigmal lobes small, barely separated (Fig. 113 a, c); in lateral view, lobe erect with posterior margin curving medioposteriorly (Fig. 113 g).

Variation in paratypes. Little variation was observed in the paratype series. One male (Sierra de Huauchinango) had a small indication of a forked humeral stripe; another male (same locality) had reduced black abdominal markings thus isolating black postbasal streaks on S4–5 similar to S 4 in Fig. 19. The small lateral lobes on the genital ligula of the holotype (Fig. 137 b) are adjacent to the sides of the ligula, but in paratypes they are usually separated basally as in A. elongata (Fig. 132 b). Females can be blue (Fig. 43) or brown. Pterostigma surmounting 1–2 cells in males and females; postnodals: Fw 16–20 in males and females, Hw 12–18 in males, 15– 17 in females; postquadrangular cells Fw 3–5, Hw 3–4 in males, Fw 4, Hw 3 in females; RP2 at Fw 7–8, Hw 6–7 in males and females. Dimensions. ♂: Hw 23 ± 1.95 [20–24], abdomen 30.3 ± 1.69 [27.6–33.1], total length 38.4 ± 2.17 [35.4–41.9]; ♀: Hw 24.8 ± 1.74 [22.3–26.5], abdomen 29.4 ± 2.11 [28.6–31.3], total length 37.7 ± 2.73 [33.5– 40.1].

Diagnosis. This species may be confused with three other largely blue species, two of which, A. anceps and A. westfalli, are sympatric with A. rudolphi (Fig. 168). The cerci in male A. rudolphi are more approximate, with their inner surfaces nearly touching in normal position (Fig. 154 c); in both A. anceps (Fig. 155 c) and A. westfalli (Fig. 157 c), the cerci are widely separated by a gap subequal to the basal width of each cercus. In dorsomedial view, the cercus of A. rudolphi (Fig. 154 d) is less elongate than in either A. anceps (Fig. 155 d) or A. westfalli (Fig. 157 d). The nearly approximate condition of the cerci in A. rudolphi (Fig. 154 d) is similar to that of the more southerly (Costa Rica to Colombia) A. fissa Selys (Fig. 156 c), but the transverse width of the torus in A. fissa (Fig. 156 c) is subequal to the transverse width of each cercus; in A. rudolphi the transverse width of each torus is about half the transverse width of each cercus (Fig. 154 c). The tip of the terminal segment of the genital ligula in A. rudolphi is short and narrow, ending in a more or less ridged trough-shaped tip (Fig. 137); the tip in the other three species is longer and flexible and can assume the shapes illustrated here ( A. anceps Figs. 134–136; essentially the same for A. fissa and A. westfalli). The ectobasal portion of the terminal segment of the genital ligula in A. anceps (Fig. 134 a, b), A. fissa, and A. westfalli has a prominent narrow mound-like lobe that is absent in A. rudolphi (Fig. 137 a, b). The following field markings will also distinguish male A. rudolphi from A. anceps, A. fissa and A. westfalli: The black postbasal streaks (sometimes extensive) present on S 4–6 in A. rudolphi (Fig. 19) are absent in A. anceps (Figs. 20; 181), A. fissa (Figs. 21; 183) and A. westfalli (Figs. 22, 23); the wings are hyaline in A. rudolphi and strongly tinged with yellow in A. anceps, A. fissa (Figs. 181–183) and A. westfalli; and the pale coloration is violaceous blue in A. rudolphi and vivid blue in A. anceps, A. fissa and A. westfalli .

The large erect oval mesostigmal plates in A rudolphi (Fig. 113) are almost approximate and are similar only to those of A. fissa (Fig. 116) and, to a lesser extent, A. westfalli (Figs. 117, 118) and A. anceps (Figs. 114, 115). A transverse swollen tubercle is present at the base of the mesostigmal lobe in posterior view in A. anceps (Fig. 115 e); no tubercle is present in A. rudolphi (Fig. 113 e), A fissa (Fig. 116 e) or A. westfalli (Figs. 117 e, 118e). In A. rudolphi, the medial margin of the mesostigmal lobe is swollen and slightly recurved (Fig. 113 d, e); no such swollen area is present in A. fissa (Fig. 116 e) or A. westfalli (Figs. 117 e, 118e). In the field, females of A. rudolphi (Fig. 43) are easily distinguished from those of the other three species (Figs. 44–46; 181–183) by the overall more extensive dark markings on the head (mostly black epicranium), thorax (prominent middorsal and humeral stripes), and abdomen (postbasal streaks coupled with distal and ventral black); the other three species are almost immaculate, there being only vestiges of black on the epicranium, a thin middorsal thoracic stripe, a narrow to absent humeral stripe, and vestiges of a distal black spot laterally on abdominal segments. The ovipositor in A. rudolphi is black (Fig. 92), not pale as in the other three species (Figs. 93–95).

Habitat. Streams and drainage areas. Specimens were taken at elevations ranging from about 570 m (Sierra de Huauchinango) to 1,300 m (stream with cascade 7 km N of Tlanchinol). Specimens have been collected in May (Sierra de Huauchinango) and July (stream with cascade 7 km N of Tlanchinol).

Distribution. Limited to a small area in the Atlantic slope of central Mexico within Puebla, Hidalgo, and Veracruz states (Fig. 168), where it occurs in sympatry with A. anceps and A. westfalli .