Yoraperla uenoi (Kohno, 1946)

Mtow, Shodo & Tsutsumi, Tadaaki, 2021, First instar nymphs of two peltoperlid stoneflies (Insecta, Plecoptera, Peltoperlidae), Deutsche Entomologische Zeitschrift 68 (1), pp. 179-188 : 179

Yoraperla uenoi (Kohno, 1946) Figs 3A-D , 4C, F, G

Description.

Body broad and slightly cockroach-like, uniformly white, covered by brownish, long and short, stout setae, without gill and ocelli (Fig. 3A, B ). Head orthognathous, trapezoidal, and highly shortened (Fig. 3A ). Antenna nine-segmented, same as half of body length (Fig. 3A, B ; Table 1 ). Compound eye reddish-black but ommatidia inconspicuous in fixed specimens; according to Mtow and Machida (2018), four ommatidia formed in full-grown embryos of Y. uenoi . Labrum slightly trapezoidal, covering part of mandible (Fig. 3C ). Mandible well-developed with teeth at its apex (Fig. 3C ). Maxillary coxopodites divided into distal cardo and proximal stipes, but latter hardly visible from ventral view (Fig. 3C ); maxillary palp and endites of maxilla, lateral galea, and mesal lacinia well developed (Fig. 3C ); teeth formed at tip of lacinia (Fig. 3C ). Labial coxopodites divided into proximal postmentum and distal prementum, but hardly recognizable in fixed specimen (Fig. 3C ); labial palp and endites of labium, lateral paraglossa, and mesal glossa well developed (Fig. 3C ). Pronotum rectangular with corners slightly rounded, slightly wider than head and wider than abdomen (Fig. 3A ; Table 1 ). Mesonotum and metanotum trapezoidal, slightly widening posteriorly (Fig. 3A ). Thoracic appendage consisting of coxa, trochanter, femur, tibia, tarsus with three tarsomeres, and pretarsus with ungues (Fig. 3D ); tibia almost identical in length to femur (Fig. 3D ); two claws can be recognized from ventral view (data not shown). Abdominal segments with a row of long and short stout setae along posterior margin of each tergum, except first to third terga, covered by metanotum (Figs 3A , 4F ); first terga without setae, second and third tergum with setae barely visible in section (data not shown). Coniform chloride cells approximately 10 µm in diameter and 1.5 µm in height distributed on posterior margin of second to ninth abdominal segments; one pair on second sternum; three pairs on third sternum; four pairs on fourth to seventh sterna; three or four pairs on eighth sternum; two pairs on ninth sternum (Fig. 4C, F, G ). Cerci three-segmented, with a crown of long and short stout setae on posterior margin of first two segments; short stout setae on apex of third segment (Fig. 3A ).

Figures

Figure 3. First instar nymphs of Yoraperla uenoi. A. Habitus, dorsal view, scanning electron microscopy (SEM); B. Habitus, dorsal view, same specimen as in (A), light microscopy; C. Mouth parts, ventral view, SEM, right side of maxillary pulp artificially lacking; D. Middle leg, SEM. Abbreviations: An, antenna; Ce, cercus; Cx, coxa; Fe, femur; Ga, galea; Gl, glossa; H, head; La, lacinia; LbP, labial palp; Lr, labrum; Md, mandible; Msn, mesonotum; Mtn, metanotum; Pgl, paraglossa; Pta, pretarsus; St, stipes; Ta, tarsus; Ti, tibia; Tr, trochanter. Scale bars: 100 µm (A, B); 20 µm (C, D).

Figure 4. Chloride cells of first instar nymphs of Microperla brevicauda and Yoraperla uenoi, anterior to the left. A. Abdomen of M. brevicauda, lateral view, stained with Mayer's acid haemalum; B, C. Horizontal sections of fifth abdominal segment of M. brevicauda (B) and Y. uenoi (C); D, E. Abdomen of M. brevicauda, lateral view, scanning electron microscopy (SEM), all abdominal segments (D) and enlargement of chloride cells (E); F, G. Abdomen of Y. uenoi, ventrolateral view, SEM, all abdominal segments (F) and enlargement of chloride cells (G). Arrowheads show the chloride cells. Abbreviations: A 1, 2, 3, 5, and 10: first, second, third, fifth and tenth abdominal segments, respectively; Ce, cercus; Mtn, metanotum. Scale bars: 50 µm (A, D, F); 10 µm (B, C, E, G).