Journal Of Entomology And Zoology Part 2

Body very long and slender, glabrous; spiracular disk obliquely truncated, surrounded by four slender naked lobes; mentum with three subequal primary teeth and a much reduced lateral tooth on either side.

_Dicranoptycharia._

PUPAE

1. p.r.o.notal breathing-horns branched; aquatic.

_Antocharia._

p.r.o.notal breathing-horns not branched; semiaquatic or terrestrial.

2. p.r.o.notal breathing-horns distinct, elongate-cylindrical.

_Rhamphidaria._

p.r.o.notal breathing-horns apparently lacking, microscopic.

_Dicranoptycharia._

THE SUBTRIBE DICRANOPTYCHA

A Key to the Species of Dicranoptycha

LARVAE

1. Spiracular disk with the dark markings less extensive; the mark of the lateral lobes not contiguous with the spiracle or the triangular area on the disk; dorsal marking indistinct or lacking.

_D. winnemana_ Alex.

Spiracular disk with the dark markings more extensive; the mark of the lateral lobes suffusing the ventral inner margin of the spiracle and usually closely approximated or nearly contiguous with the triangular area on the disk; dorsal marking black, transversely rectangular.

_D. minima_ Alex.

Description of the Species.

DESCRIPTION OF THE SPECIES

1916 _Dicranoptycha winnemana_ Alexander; Proc. Acad. Nat. Sci. Phila., pp. 500, 501; Pl. 25, fig. 12.

_Larva._--Length, 20-22 mm.

Diameter, 0.9-1.1 mm.

Coloration varying from white to almost black depending on the nature and amount of the food eaten which shows clearly through the transparent integument. The fat-bodies likewise show through and give a white color to the larva especially after death.

Form very elongate (fig. 1), body terete; integument very glabrous, transparent and gla.s.sy. Prothoracic segment a little longer than the mesothorax which, in turn, slightly exceeds the metathorax. The intermediate abdominal segments are elongated. The basal ring of sternites two to eight bears a transverse band or area of microscopic chitinized spicules, the one on the eighth segment split lengthwise by a capillary line. A similar band occurs in the same position on the dorsum of the eighth segment but the pleural region is devoid of such a band.

Spiracular disk (fig. 8) moderate in size, obliquely truncated, surrounded by four lobes, a pair of small, slender, lateral lobes and short, broader ventral lobes. The usual dorso-median lobe is lacking but its position is indicated by a gently rounded convexity. The inner face of the lateral lobe bears a narrow semi-lunate black mark with the concavity toward the spiracle, the proximal end acutely pointed. The ventral lobes bear a similar but smaller subrectangular black mark. A pale and usually indistinct dusky mark occupies the inner face of the dorsal lobe. On the disk between, and slightly below the level of, the spiracles is a large brown triangular or V-shaped mark. The spiracles are small, separated from one another by a distance equal to about 2.5 to 3 times the diameter of one; the center-piece of the spiracle is black, the ring yellow surrounded by an outer dusky margin. a.n.a.l gills fleshy and protuberant as a blunt ring surrounding the a.n.u.s (fig. 10).

Head-capsule (fig. 2) of the compact, ma.s.sive type of the Limn.o.biini; praefrontal sclerite (fig. 3) large and distinct; the sclerite broad with the sides subparallel to about midlength, thence tapering gradually to the tip which is entire; there are two or three punctures at the margin before midlength. Interno-lateral plates narrow, a little longer than the praefrons; externo-lateral plates very broad, thin and flattened with the posterior margin very obtuse and the inner ventral portions continuous with the mental plate. Labrum (fig. 3) very broad and extensive, flattened, pale in color, the anterior margin with about two sense-organs. Mentum (fig. 4) deeply split behind but not completely divided, the anterior margin with three primary teeth that are subequal in size or the middle one a little smaller; a much reduced lateral tooth on either side. Praementum smaller than the hypopharynx, in outline roughly oval or semicircular with the two l.a.b.i.al palpi surrounded by hairs at the base. Hypopharynx (fig. 5) consisting of two chitinized arms that are contiguous but not fused medially, the concavity between them filled with a rounded cushion that is covered with tubercles arranged in more or less distinct oblique parallel rows.

Antennae (fig. 6) two-segmented, the basal segment cylindrical with an auditory plate on the face at beyond midlength; apical segment long and slender, in length but slightly less than the basal segment, tapering gradually to the bluntly rounded apex. Mandibles (fig. 7) simple with the teeth blunt; apical point longer than the lateral teeth; dorsal tooth single, broad, very flattened and obtusely pointed; ventral teeth two, a little smaller than the dorsal tooth. Maxillae (fig. 2) of a generalized structure, the cardines distinct and feebly chitinized; distal lobes of the organ consisting of a subequal inner and outer lobe; the outer lobe with an abundance of long, delicate hairs and bearing a few sensory papillae including one larger palpiform organ.

_Pupa._--Length, 9.1-12.8 mm.

Width, d.-s., 1.6-1.8 mm.

Depth, d.-v., 1.6-1.9 mm.

Thoracic dorsum shiny light brown; in very old pupae the color is much darker, but still retains a much brighter color than the leg and wing-sheaths; abdomen pale becoming darker in age, especially on the pleura.

Cephalic crest (fig. 13) low and depressed, inconspicuous, lying between the antennal bases which extend beyond it; there are four small setigerous lobes, the larger pair of which are posterior in position.

Front between the eyes broad, subparallel. Two blunt tubercles on either side of the forehead. Eyes large, with coa.r.s.e ommatidia. Labrum semicircular in outline, tumid. l.a.b.i.al lobes large, oval, contiguous with one another, at the tip of the labrum. Maxillary palpi moderately long and slender, nearly straight, gradually narrowed to the tip which ends opposite the knee-joint of the fore legs. Antennae with the basal segments separated only by the cephalic crest, the sheaths ending about opposite or a little before the lateral angle of the thorax.

p.r.o.notal breathing-horns (fig. 14) very small, almost microscopic; when viewed from the dorsal aspect appearing as tiny triangular tubercles.

Mesonotum moderately convex, unarmed, the V-shaped suture distinct; a few setae on the mesonotum, including one near the end of each scutal lobe. Wing-sheaths rather short, but narrow, ending about opposite midlength of the third abdominal segment. Leg-sheaths ending opposite the base of the fifth abdominal segment, the tips of the tarsi ending about on a common level or those of the fore legs a trifle longer.

Abdominal segments (fig. 11) subdivided into four annuli that bear transverse bands of microscopic setae; these bands increase in width from the basal to the apical. Spiracles on the pleural region of segments two to seven, lying opposite the third annulus and close to the ventral margin of the pleura. No spiracles are discernible on the dorsum of the eighth segment. Male cauda (fig. 11) with the ventral lobes very blunt, rounded; the dorsal lobes very small, terminating in a sharp spine that is directed dorsad and bears a weak seta near its base. Female cauda (fig. 12) with the ventral lobes a little longer than the dorsal lobes; the latter at the outer angle of the apex with a short stout spine that is directed dorsad as in the male.

_Nepionotype_ (type larva), Lawrence, Kansas, April 2, 1918.

_Neanotype_ (type pupa), with the type larva, May 6, 1918.

_Paratypes_, larvae and pupae, about fifty from the type locality, March 20 to May 20, 1918.

_Dicranoptycha minima_ Alexander.

1919 _Dicranoptycha minima_ Alexander; Ent. News, Vol. 30.

The larva is very similar to that of _D. winnemana_ as described above, but is slightly smaller. The spiracular disk (fig. 9) has the dark markings much more extensive. The mark of the lateral lobes is contiguous with the spiracles and is also closely approximated to the large triangular brown mark on the disk. There is a large transverse rectangular mark occupying the inner face of the dorsal lobe. The marking of the ventral lobe is about as in _D. winnemana_.

_Nepionotype_, Lawrence, Kansas, July 11, 1918.

_Neanotype_, Lawrence, Kansas, July 21, 1918.

_Paratypes_, a few larvae from the type-locality.

Explanation of the Figures

A--l.a.b.i.al Lobes; E--Eye; EL--Externo-lateral Plate; G--a.n.a.l Gills; IL--Interno-lateral Plate; Lb--Labrum; M--Maxillary Palpus; P--p.r.o.notal Breathing-horn; Pf--Praefrons; S--Spiracle.

Fig. 1. Larva of _Dicranoptycha winnemana_, ventral aspect of body.

Fig. 2. The same, head-capsule, ventral aspect.

Fig. 3. The same, head-capsule, dorsal aspect.

Fig. 4. The same, mentum, ventral aspect.

Fig. 5. The same, hypopharynx, ventral aspect.

Fig. 6. The same, antenna.