Bittacus planus, Cheng, 1949

Jiang, Lu & Hua, Bao-Zhen, 2015, Functional morphology of the larval mouthparts of Panorpodidae compared with Bittacidae and Panorpidae (Insecta: Mecoptera), Organisms Diversity & Evolution (New York, N. Y.) 15 (4), pp. 671-679 : 673-674

Mouthparts of B. planus

The labrum is furnished apically with two pairs of labral setae and numerous microtrichia. The inner pair of setae is approximately two thirds the length of the outer pair ( Fig. 3a : ls).

The epipharynx is grossly subdivided into a terminal rectangular plate and a proximal triangular plate, both furnished with numerous lateral microtrichia and various types of sensilla ( Fig. 3b ). Uniporous sensilla basiconica are arranged into two groups: three pairs on the apex of the epipharynx and four pairs on the inner surface ( Fig. 3b : sb). The epipharynx is also furnished with two pairs of palmate sensilla on the lateromedial part ( Fig. 3b, c : ps). The triangular plate is encompassed by two rows of spines and a basal tuft of microtrichia. This plate is equipped laterally with a pair of palmate sensilla ( Fig. 3d : ps) and a pair of prominent sensory protuberances ( Fig. 3d : sp), each bearing one larger and three smaller sensilla basiconica ( Fig. 3d : sb).

The mandible is curved, tapers apically, and bears two distal cusps and a sharp cutting edge at the incisor region ( Fig. 3e–g : ce/ir). The molar region is furnished with tuberculate molar teeth ( Fig. 3h : mt), which are bordered laterally by long stiff spines ( Fig. 3h : s). The mandible bears a tuft of hair brush ( Fig. 3h : hb) sensu Lawrence (1991) on the baso-mesal corner and three long sensilla trichodea laterally. The middle one is shorter and setiform, and the basal two are longer and brush-shaped apically ( Fig. 3f ).

In total, the maxilla bears eight sensilla chaetica on the ventral surface: three on the cardo-stipes, one on the basal palpomere, two on the second palpomere, and two on the galea ( Fig. 4a : sch). The galea bears dorsally numerous microtrichia and sensilla ( Fig. 4b ), including five sensilla basiconica on the apical half ( Fig. 4c : sb) and two sensilla campaniformia on the basal half ( Fig. 4d : sco). The lacinia is equipped with stiff spines directed mesally ( Fig. 4b : s). The maxillary palp bears 14 sensilla basiconica apically ( Fig. 4e ).

The labium is remarkable for the hirsute prementum ( Fig. 4a : prm), which is furnished with tufts of long microtrichia. The basal segment of the labial palp has mesally a short sensillum chaeticum subapically, and the apical segment has nine sensilla basiconica apically ( Fig. 4f ).

Figures

Fig. 3 Mouthparts of Bittacus planus. a Labrum. b Epipharynx. c Lateral palmate sensilla. d Sensory protuberance. e–h Mandibles, dorsal (e), ventral (f), and mesal views (g) and magnified aspect of the molar region (h). cd condyle, ce cutting edge, gg ginglymus, hb hair brush, ir incisor region, ls labral seta, mr molar region, mt molar teeth, ps palmate sensillum, s spine, sb sensillum basiconicum, sp sensory protuberance

Fig. 4 Mouthparts of Bittacus planus. a Mouthparts, ventral view. b Maxilla, dorsal view. c Sensilla basiconica on maxilla. d Sensilla campaniformia on maxilla. e Apex of maxillary palp. f Apex of labial palp. cas cardo- stipes, ga galea, la lacinia, lp labial palp, mp maxillary palp, pm postmentum, prm prementum, s spine, sb sensillum basiconicum, sch sensillum chaeticum, sco sensillum campaniformium, so salivary orifice