Turquoise Tipped Darner

Aeshna (Hesperaeschna) psilus PI. XL, fig. 531, PL XLI, figs. 539-554;
Material studied. — Costa Rica : Juan Vinas, laguna, 2 $ exuviae, May 4, 1910; Cartago, exuviae of Aug. 22-23 (6-ult), Aug. 26-27 (5-ult), between Aug. 31 and Sept. 10, Sept. 13-17 (4-ult), Oct. 10-12 (3-ult), Xov. 10-12 (penult), 1909, Jan. 6-16, 1910 (ult) of 2 larvae collected Aug. 20, 1909, one died Sept. 26 in moulting. British Guiana : Mt. Roraima 1932, J. G. Myers 1 9 larva, #3266. Cuba : Camaguey 18.iv.'30 1 $ larva nearly full-grown, coll. J. G. Xeedham. Total 12+1 larva, 6 S exuviae.
Some developmental changes in the larval period of psilus are set forth below.
1. The youngest stage represented in our material is an exuvia of Aug. 22-23, 1909, of the 8ult instar of our nomenclature.* It is in fragments and has been mounted in balsam. Its fragmentary condition precludes the giving of all but a few dimensions. There are granulations on the lateral posterior angles of the head, many facets to the compound eyes. Mandibles with four subequal distal teeth (incisors) and one proximal (molar) with an anteapical tooth. Inner lobe of maxillae with five curved acute spines. Labial palps : fixed hook with setae near base of movable hook which are not as long as the width of the segment, apex squarely truncated. Distal margin of mentum with an acute tooth each side of the open median (ligular) cleft. Femora and tibiae not annulate, tarsi 2-segmented. Lateral spines on abd. segs. 7-9.
2. Xext in age are two exuviae of Aug. 26-27, 1909. Total length 11.00 mm., head: maximum length 1.51-1.75, maximum width 3.67, hind dorsal margin 1.61-1.70, 4 antennal segments, mandibles with four incisors, one longer than the others, inner lobe of maxillae with six curved acute spines ; mentum : length 1.80 mm., width at base .71, at mid-length .95, at distal end 1.46. Labial palps : dorsal surface of fixed hook as stated for preceding instar, movable hook .39 mm. long, with setae not as long as width of hook. Hind wingpads reaching to mid-length or hind margin of abd. seg. 1, their front margin .5-. 58 mm. Femora and tibiae faintly annulate, tarsi 2-segmented. Mid-dorsal length of abd. seg. 8 .71 mm., of 9 .61, of 10 .33, lateral spines on 6-9, their relative lengths from greatest to least 9, 8, 7, 6, those on 9 reaching to midlength of 10. Anal apps. : mid-dorsal .5-.65 mm., its apex roundly excised, an acute spine at each lateral apical angle, lateral ("cercoids") .30 mm., inferiors ("cerci") .78-1.08.
*Anat. Record 31 (4): 327, 1925; Univ. Iowa Studies Nat. Hist. 12(2): 1415, 1928. 3. A 6ult exuvia shed between Aug. 31 and Sept. 10, 1909, is in fragments so that few dimensions can be taken. Head : maximum width 3.68 mm., hind dorsal margin 1.89, mandibles as stated for the preceding instar, granulations (spinules .0233 mm. long) on the lateral posterior angles of the head, facets of the compound eye numerous, hind wing-pads, front margin 1.51 mm. long, tarsi 3-segmented, inferior anal apps. 1.61 mm.
4. A 5ult exuvia shed between Sept. 13 and 17, 1909. Total length 16 mm., head : maximum length 2.62 mm., maximum width 3.44, hind dorsal margin 1.92, antennal segments 5, labium at rest reaching to hind edge of prosternum ; mentum : length 2.25 mm., width at base .93, at mid-length 1.21, at distal end 1.86, distal margin with two teeth, each .01 x .032 mm. and .02 mm. from the closed ligular cleft. Labial palps : fixed hook squarely truncated at level of ligular cleft, its posterior mesal angle barely prolonged, slightly acute. Hind wing-pads reaching to a little beyond the base of abd. seg. 2, their front margin .96 mm. Tarsal segments 2-3-3. Abdomen : maximum width 4.66 mm. at seg. 6, mid-dorsal length of seg. 9 .80, of 10 .95 ; gonapophyses .04 mm., mid-ventral length of 9 .85 ; lateral spines on 6-9, their relative lengths from greatest to least 9, 8, 7, 6. Anal apps.: mid-dorsal .93 mm., its apex with notch .11 mm. deep, an acute spine at each lateral apical angle ; lateral apps. .70 mm., inferiors 1.42; ratio of length of mid-dorsal to length of inferiors .65.
5. A larva which died in moulting Sept. 26, 1909, has a total length of 19 mm.; head: maximum length 3.12, maximum width 4.81, hind dorsal margin 4.73 ; antero-posterior rows of setae on the lateral posterior angles of head, many facets on the compound eyes, antennal segments 7. Supracoxal processes with the posterior division a little longer than the anterior. Hind wing-pads reaching to the middle of abd. seg. 2, their front margin 2.50 mm. Femora and tibiae not annulate, tarsal segments 3-3-3 and so to the end of the larval period. Abdomen: maximum width 1.82 mm., at seg. 6; mid-dorsal length of seg. 8 1.28 mm., of 9 1.09, of 10 1.04, gonapophyses .24, mid-ventral length of 9 1.04, lateral spines as stated for the preceding instar. Anal apps.: mid-dorsal 1.98 mm., its apex shallowly, roundly excised, .05 mm. deep, an acute spine at each lateral apical angle, male part .80 mm. long; lateral apps. 1.60 mm., inferiors 2.36 ; ratio of length of mid-dorsal to length of inferiors .84, of length of male part to length of laterals .5.
6. An antepenult or 3ult exuvia of Oct. 10-12, 1909, has lost abd. seg. 9. Head: maximum length 3.12 mm., maximum width 4.81, hind dorsal margin 2.48. spinules on the hind lateral angles ; mentum : length 3.60 mm., width at base 1.18, at mid-length 1.80, at distal end 2.46, distal margin with two obtuse teeth, one on each side of ligular cleft. Front margin of hind wing-pad 1.65 mm. Anal apps.: mid-dorsal 1.23, its male part .47 mm. long, basal width .71, lateral apps. 1.08, inferiors 2.17; ratio of length of mid-dorsal to length of inferiors .56, of length of male part to the length of laterals .44.
7. A penultimate? exuvia of Nov. 10-12, 1909, has a total length of 26 mm.; head : maximum length ca. 3.40 mm., maximum width 6.79, hind dorsal margin
ca. 3.02, granulations + setae + spinules on lateral posterior angles, facets of compound eyes numerous; mentum : length 4.25 mm., width at base 1.42, at midlength 2.41, at distal end 3.31, distal margin with a row of hairs .05 mm. long, two teeth .019 x .044 (left), .025 x .063 (right), the left .05 mm., the right .038 mm. from the closed ligular cleft. Hind wing-pads reaching to the hind margin of abd. seg. 2, their front margin 3.54 mm. Male gonapophyses .19 mm. long. Anal apps. : mid-dorsal 1.75, its male part .71, basal width .95 ; lateral apps. 1.42, inferiors 2.50; ratio of length of mid-dorsal to length of inferiors .70, of length of male part to length of laterals .50.
8. Ultimate exuvia shed between Jan. 6 and 16, 1910. Total length 30 mm.; head: maximum length 4.71, maximum width 8.04, hind dorsal margin 4.53, antennal segments 7. Mentum: length 6.14 mm., width at base 1.78, at mid length 3.11, at distal end 4.17, distal margin with a row of hairs 1 mm. long, no teeth visible in dorsal or ventral view (dry mount, under compound microscope), ligular cleft closed. Hind wing-pads reaching to hind margin of abd. seg. 4, their front margin 8.00 mm., tarsal segments 3. Abdomen : maximum width 5.85 mm. at seg. 7, male gonapophyses .33 mm., mid-ventral length of 9 1.64. Anal apps.: mid-dorsal 2.74, its apex transversely truncated, an acute spine at each lateral apical angle, its male part 1.18 mm. long, basal width 1.18, lateral apps. 2.60, inferiors 3.50, ratio of length of mid-dorsal to length of inferiors .78, of length of male part to length of laterals .45.
The total lengths of the successive exuviae of psilus are x, 11, x, 16, 19, x, 26, 30 mm. Corresponding figures of Gardner's 1950 description * of Ae. mixta are (1) pronymph, (2) 2.5, (3) 3.5, (4) 4.5, (5) 6.00, (6) 6.85, (7) 11.0, (8) 15.0, (9) 22.0, (10) 30 mm.
Aeshna (Hesperaeschna) Sp. No. 2 (Nova Teutonia, Brazil)
The following features of the ultimate larval instar are not fully mentioned in the preceding paragraph : dorsal surface of proximal segment (fixed hook) of labial palp with a proximal line of 5-7 setae, .025-. 3 mm. long, and a distal cluster of 5-7 setae, .015-. 52 mm. long; dorsal surface of distal segment (movable hook) 1.42-1.56 mm. long with 15-20 setae .04-. 38 mm. long; posterior division of supracoxal process longer than the anterior (subequal in one Juan Vihas exuvia), antenodals in the front wing pads 16 in one exuvia, uncertain in the other two, femora and tibiae annulate, mid-dorsal length of 9 -f10 2.543.03 mm., lateral spine on 6, including the terminal hair, .25-. 38 mm. long, on 8 .5-. 98, on 9 .39-. 74 mm. The ratio of the length of the middorsal appendage to the length of the inferiors, in the three reared exuviae of psilus from Juan Vihas and Cartago, varies from .675 to .76; the ratio of the length of the male part of the mid-dorsal appendage
* Gardner, A. E., 1950, Entom. Gazette I: 128-138.
to the length of the lateral appendages from .4 to .44; male part of the superior ( mid-dorsal) 1.23-1.31 mm. long, its basal width 1.23-1.31 mm. ; markings of the thorax indistinct ; apex of the superior appendage transversely truncated, each lateral angle an acute spine directed caudad.
The 9 larva from Mt Roraima probably belongs near here although it shows some slightly divergent features. It measures 23 mm. long but the terminal abdominal segments are somewhat retracted so that the total length in life was probably a few millimeters greater. Maximum width of head 4.25 mm., antennae 8-segmented, third segment longest, front margin of the hind wing pad .85 mm. long, genitalia .71 mm., mid-ventral length of abd. seg. 9 1.13, mid-dorsal appendage 2.36, its apex very acute, lateral appendages .71, inferiors 2.17 mm. These divergent features may indicate that this Mt. Roraima larva belongs to Ac. (H.) cornigera planaltica to which I referred an imago from the same locality antea, page 49. For some further data on this larva see the following paragraph.
By our key to larvae there falls also in psihis a 2 exuvia from Porto Velho. Brazil, May 5, 1922, " on under side green leaf 3" above little creek in woods 2y 2 miles SE " by J. H. Williamson, UM. Total length 32 mm., median length of head 5.48, maximum width of head 8.34, 'its hind angles distinctly rounded, basal width of mentum 2.45, distal width 5.40 hind wing pads reaching to a little beyond mid-length of abd. seg. 4, their front edge 8.57, maximum width of abdomen 6.63 at segment 6, genitalia 3.11, mid-ventral length of 9 2.29, middorsal (superior) appendage 2.54. its apex squarely truncate, lateral apps. 3.03. inferiors 3.27. femora and tibiae annulate, lateral spines on abd. segs. 5-9, those on 6 distant from the hind margin of the segment by their own length, lateral spines on 9 reaching to mid-length of 10. subequal to those on 8, ratio of the length of the mid-dorsal app. to that of the inferiors .775. Striking features are a tuft of brown hairs, 1.15 mm. long, on each side of the vertex behind the level of the basae of the antennae, and a similar tuft of brown hairs, 1.47 mm. long, on each side of the occiput a little farther apart than the preceding tufts. Xo traces of these tufts are visible in the psilus exuviae or larvae or in the Mt. Roraima larva. Instead of the posterior pair of hair tufts the Mt. Roraima larva has nine or ten antero-posterior rows of minute granulations on each half of the occiput; these rows of granulations are lacking in psilus exuviae and larvae from Costa Rica but present in the female larva from Camaguey, Cuba.
The surface of the body of the Porto Yelho exuvia is incrusted with debris; it is hence uncertain whether there are any pale dorsal abdominal stripes; lateral, latero-dorsal and dorsal puncta are visible on abd. segs. 3-8. The distal mental margin of this Porto Velho exuvia is figured on PI. XLV, figs. 600, 601, as a Coryphacschna, following
the method of Wright and Petersen. The labial palps in fig. 600 are certainly more like those of ingens, fig. 598, PI. XLV, and of viriditas, fig. 599, PI. XLV, than those of psilus, figs. 545, 541, PI. XLI, or of adncxa, fig. 588, PI. XLV. The hind angles of the head are rounded in the Porto Velho exuvia, and in the psilus exuviae from Juan Vinas and Cartago, but angulate in the ingens exuvia from North Carolina and larva from Florida, the adnexa larvae from Porto Rico and the viriditas from Fortaleza.
Aeshna (Hesperaeschna) sp. No. 1 (Porto Velho, Brazil) PL XLV, figs. 600,
601; Map 1.
Material studied. — Brazil : Porto Velho, on under side green leaf 3' above little creek in woods 26 miles S. E., May 5, 1922, J. H. Williamson, 1 9 exuvia coll. E. B. Williamson UM.
Total length 37 mm., maximum length of head 5.40, maximum width of head 8.18, hind dorsal margin ca. 5.00, concave to a depth of .33 mm. in the middorsal line ; hairs and granulations at each lateral posterior angle, arranged in 13-15 parallel longitudinal rows, alternate rows a little longer, front dorsal margin almost straight, very slightly concave. Antennal segments 7, 3rd segment longest, a little shorter than 1 + 2 ; ocelli faintly indicated, compound eyes with many facets, a small bunch of brown hairs at each side of the ocellar tubercle (vertex), a larger bunch of brown hairs on the occiput behind the mesal projection of each compound eye, this mesal projection being punctulose, not faceted, the larger bunches farther apart than those on the vertex ; labrum and nasus (postclypeus) subequally wide, rhinarium narrower, mandibles projecting laterad farther than labrum or clypeus, in ventral view angulate. Base of mentum damaged, width at mid-length 4.17 mm., at distal end 5.32, distal margin with a median, almost semi-circular cleft, .40 mm. at the margin, .2 mm. deep, the cleft with a minute dark brown tooth at each side (Figs. 600, 601, pi. XLV). Fixed hook of labial palp obliquely truncated at apex to form an acute angle, mesal margin concave, denticulated (about 15 denticles) (Fig. 600, pi. XLV) ; movable hook 2.62 mm. long, tapering throughout its length.
Pronotum and left propleura damaged, right propleura with posterior division of supracoxal process twice as long (high) and twice as wide as the anterior division and pointed caudad, right half of pronotum with a rectangular lateral process. Hind wing-pad reaching to mid-length of abdominal segment 5, its front margin 9.43 mm. long. Third femora 5.85 mm. long, all femora with three transverse dark bands, all tibiae with three dark bands, all tarsi with first segment darker, second and third segments each with a dark band.
Abdomen: maximum width 6.51 mm. at segment 6; the surface of the body is encrusted with debris ; it is hence uncertain whether there are any pale dorsal abdominal stripes ; dorsal, latero-dorsal and lateral puncta are visible on segments 3-8. Genitalia 3.11 mm. long, mid-ventral length of abd. seg. 9 2.29. Lateral spines on segments 5-9, shortest (.19 mm.) on 5, those on 6 half as long as the intersegmental area 6-7, those on 9 reaching to mid-length of 10 and subequal to those on 8. Anal appendages : mid-dorsal 2.45 mm. long, longer than segment 10, shorter than 9+10, apex transversely truncated. Lateral (left, right broken) 3.03 mm., inferiors 3.27, ratio of the length of the middorsal to that of the inferiors .775.

Aeshna psilus Calvert

Aeshna cornigera, nec Brauer.—Klots, 1932, p. 18.

Aeshna psilus Calvert, 1947, p. 4.—Calvert, 1956, p. 150.

MATERIAL EXAMINED.—Dominica: Brantridge, 9 May 1964, 1 nymph(OF); Freshwater Lake, 5 June 1964, 1 ,1(TD), 7 June 1964, 1 (TD), 15 Oct. 1966, 1 (ET).

This species is recorded from the Lesser Antilles for the first time, having previously been known from the Greater Antilles, Mexico, Central America, and northwestern South America. It is less conspicuous than the previous species, and prefers to patrol paths and wet spots around the lake, rather than the open water.

Rhionaeschna psilus, the turquoise-tipped darner, is a species of darner in the family Aeshnidae. It is found in the Caribbean, Central America, North America, and South America.

The IUCN conservation status of Rhionaeschna psilus is "LC", least concern, with no immediate threat to the species' survival. The population is stable.