Microperla brevicauda Kawai, 1958

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

Microperla brevicauda Kawai, 1958 Figs 2A-D , 4A, B, D, E

Description.

Body slender, uniformly white, sparsely covered by long and short fine setae, without gill and ocelli (Fig. 2A, B ). Head prognathous, subtriangular (Fig. 2A, B ). Antenna nine-segmented, longer than two-thirds of body length (Fig. 2A, B ; Table 1 ). Compound eye reddish-black with four ommatidia. Labrum nearly semicircular, covering part of mandible (Fig. 2C ). Maxillary coxopodites divided into distal cardo and proximal stipes (Fig. 2C ); maxillary palp and endites of maxilla and lateral galea well developed, but mesal lacinia hardly visible externally (Fig. 2C ). Labial coxopodites divided into proximal postmentum and distal prementum, but hardly recognizable in fixed specimen (Fig. 2C ); labial palp and endites of labium, lateral paraglossa, and mesal glossa well developed (Fig. 2C ). Pronotum rectangular, almost same width as the head, and wider than the abdomen (Fig. 2A ; Table 1 ). Lateral margin of mesonotum and metanotum less developed (Fig. 2A ). Thoracic appendage consisting of coxa, trochanter, femur, tibia, tarsus with three tarsomeres, and pretarsus with ungues (Fig. 2D ); tibia longer than femur (Fig. 2D ). Abdominal segments with a row of long fine setae along posterior margin of each tergum (Figs 2A , 4A ). Coniform chloride cells approximately 10 µm in diameter and 1 µm in height distributed on lateral side of first nine abdominal segments; one pair on first, eighth, and ninth targa; two pairs on second to seventh segments, i.e., one pair on each of second to seventh terga and sterna (Fig. 4A, B, D, E ). Less sclerotized supraanal lobe on hind margin of tenth tergum (Fig. 2A ). Cerci four-segmented, with a crown of long and short fine setae on posterior margin of first three segments; short fine setae at apex of fourth segment (Fig. 2A ).

Figures

Figure 2. First instar nymphs of Microperla brevicauda. 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; D. Middle leg, SEM. Abbreviations: An, antenna; Ca, cardo; Ce, cercus; Cx, coxa; Fe, femur; Ga, galea; Gl, glossa; H, head; LbP, labial palp; Lr, labrum; Md, mandible; Msn, mesonotum; Mtn, metanotum; Pgl, paraglossa; Pta, pretarsus; Spa, supraanal lobe; 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).