The highly elongated outer edges of the posterior tentorial pits partly coincide with this suture. The two sclerites are separated on the dorsal surface of the skull by the median coronal suture. The compound eyes (eye) are located on the prominent anterolateral corners of the head.
Each pleurostoma is an extremely small, elongate clerite that arises at the base of the mandible and extends to the ventral outer edge of the anterior tentorial fossa. From these points of attachment, the forelimbs converge posteriorly to join the corporotentorium in the center of the head. The corporotentorium (ct) is located in the center of the head and has a transverse shape.
Each mandible articulates dorsally on the base of the clypeus and ventrally by means of a conspicuous condyle (co) on the lower edge of the skull. In the retracted position, the cardo is folded dorsally over the stipes, where it articulates on the anterior border of the posterior tentorial pit. In protraction, the prementum is thrust over the head by a forward swing of the postmentum.
The ligula (light) lies between the bases of the palpi and is fused with the prementum.
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CERVIX OR NECK
THORAX
NO. II NAIADS OF DRAGONFLY GENUS PLATHEMIS — LEVINE II
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The scutum (sct2), the largest sclerite of the tergum, is a longitudinally elongated, posteriorly converging, weakly sclerotized lobe in the membranous region between the anterior wing bases. The episternum (eti) is a relatively very small area bounded anteroventrally by the precoxal bridge and posteriorly by the epimeron. The marginally setiferous precoxal bridge (pr) is well sclerotized and united ventrally with the basic ternum.
It is separated posteriorly from the mesothoracic catephisternum by the peritremal plate of the mesothoracic spiral above and a flexible, wrinkled, partially sclerotized area below. Each pleuron is divided into two main regions, episternum and epimeron, by a pleural suture (pls2) that extends obliquely posterodorsad from the pleural coxal process to the base of the wing.
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II NAIADS OF DRAGONFLY GENUS PLATHEMIS — LEVINE 15 marked by lateral parts of sternocostal suture (scs3). The catepimeron (kem3), or the ventral part of the epimeron, has been completely isolated on the sternal surface due to the engagement of the large poststernum posterior to the coxal cavity. Thebasisternum (bs^, the largest prosternalarea, is fused anterolaterally with the precoxalia (pr) of the episternum and posteriorly with the small furcasternum.
The furcasternum (fsi) is a small transverse region located between the proternal fural pits (fpi), the external manifestations of the endoskeletal furcal apophyses. The metathoracic sternum (Fig. 17) consists of two sclerites, the basal sternum and the poststernum (Asahina, .. I954)> which are completely separated by the medioventral con-. The basic ternum (bs3) is a small, transversely elongated region in the anterior part of the metasternum, located between the ventrally extended portions of the metapleural katepisterna.
It is roughly triangular in plan, with the obtuse apex directed forward and the basal angles reflected. The fureal pits (fp3) have become isolated and lie in the lateral ends of a deep flexure that partially separates the ventrally reflected episternal and epimeral plates. One distinct axillary clerite is present at the base of the adult wing (Snodgrass, 1909), but this sclerite is not marked in the naiad.
Wing tracheation: Adult wing veins are preceded by tracheae on the wing pads of nymphs. These tracheae are indicated externally on the wing pad surface by rows of well-developed setae. The tracheae themselves are best observed in freshly killed specimens in which the tracheae are filled with air (Needham, 1903), but the present writer observed the tracheae through the morphologically ventral surface of the left wing pad making dried specimens of transparent with the addition of alcohol or xylene. .
II NAIADS OF DRAGONFLY GENUS PLATHEMIS – LEVINE 17of the costal margin and a very small branch posteriorly to connect.
NO. II NAIADS OF DRAGONFLY GENUS PLATHEMIS — LEVINE 17 of the costal margin and a very minute branch posteriorly to connect
The basal end of the coxa is bounded by a submarginal basicosteal suture (bcs), which internally forms a submarginal basicosteal ridge and initiates a narrow marginal flange, the basicoxit (bcx), which is enlarged on the outer surface posterior to the pleural articulation. The deeply emarginate dorsal margin of the thecoxa allows for a wide range of motion of the legonet this dicondylar hinge. This acts at right angles to the coxotrochanteral hinge, but allows much freedom than the latter since almost entirely distally.
In addition, the posterior surface of the prothoracic femur, the anterior and posterior surfaces of the mesothoracic femur, and the anterior surface of the hind femur are also provided with numerous setae and spines. This is apparently correlated with the natural position of the legs; front legs held forward, middle legs held posteriorly^ and hind legs held posteriorly. Numerous medium to long spines and setae are borne on both the dorsal and ventral tibial surfaces, the heaviest spines being present on the ventral surface near the distal margin.
The claws or ungues (un) are the largest parts of the pretarsus, and they articulate with a small dorsal process of the distitarsus. The ungitractor is a sclerite that can be pulled onto the distitarsus by muscle action on the tibia. An empodium (emp) is attached to the distal end of the unguitractor by a narrow stalk.
ABDOMEN
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NO. II NAIADS OF DRAGONFLY GENUS PLATHEMIS — LEVINE 21
ANAL APPENDAGES
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COMPARATIVE ANATOMY OF THE GENUS PLATHEMIS
Garman (1927), in his description of Plathemis lydia, states that the dorsal hooks are present on segments 3 to 5 or 6. The author found that in both species the dorsal hooks are always and only present on segments 3-6. In Plathemis lydia, the dorsal hooks are present on abdominal segments 3 to 6, the longest on segment 5.
TAXONOMY AND DISTRIBUTION
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PREVIOUS SPECIFIC DESCRIPTIONS
DISTRIBUTION AND DATES
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NO. II NAIADS OF DRAGONFLY GENUS PLATHEMIS — LEVINE 27
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