Babalimnichus masamii M. Satô (1994:175)

Yoshitomi, Hiroyuki & Satô, Masataka, 2001, Description Of The Larva Of Babalimnichus Masamii M. Satô (Coleoptera: Limnichidae, Thaumastodinae), The Coleopterists Bulletin 55 (4), pp. 471-474 : 472-473

Babalimnichus masamii M. Satô (1994:175)

Mature Larva. Body length about 2.0 mm; body width about 0.4 mm (at prothorax); head length about 0.2 mm; head width about 0.3 mm. Head and mouth parts brown, but mandible somewhat dusky; dorsal surface of thorax and abdomen pale brown; ventral surface of thorax and abdomen cream colored; front leg yellowish brown, but claw somewhat dusky; middle and hind legs cream colored, except for brown claws.

Head ( Fig. 2 ) wider than long, covered with long and short setae; gular sutures absent. Antenna ( Fig. 4 ) short; scape with two large punctures; flagellum with an apical spine; sensorium large, almost same size of pedicel. Four stemmata forming quadrangle on each antero­lateral side of head; one of them situated just behind antennal base; another one just below it, behind base of mandible; other two stemmata behind each anterior ones. Labrum ( Fig. 5 ) a little wider than long; front margin provided with eight short setae; lateral margin with unique type of three setae on each side, anterior one strong, two remaining posterior setae long and pectinate; three dorsal setae on each side long; a pair of long apodemes protruding from near antero­lateral corners. Mandible ( Fig. 6 ) rather strong, with two apical teeth; a pectinate and articulated basal setose process connecting at about the basal 1/4 of inner margin of mandible. Maxilla ( Fig. 3 ) with four segmented palpi; galea articulated, with six strong setae; lacinia fixed, with a unique type apical seta. Mentum with a pair of long setae slightly lateral to and beside the middle. Gula present. Thorax wider than head, covered with long and short setae; prothorax widest segment of the body. Legs long; front leg ( Fig. 7a ) stouter than the other legs, covered with several strong setae on ventral surface of tibia and tarsus, with a strong seta and a small process on pretarsus; middle ( Fig. 7b ) and hind legs ( Fig. 7c ) slender, with a normal seta on pretarsus. Abdomen cylindrical, covered with long and short setae; 9th tergite without distinct urogomphus, with some setae longer than setae on abdominal segments.

Comparisons to Other Limnichid Larvae. This larva is distinguished from other limnichid larvae which have been described in the following points: 1) front leg is stouter than the other legs; 2) two setae on lateral margin of labrum are long and pectinate; 3) labrum has a pair of apodemes; 4) each mandible has a pectinate and articulated basal setose process. The last characteristic in this species is very interesting and important, because the other described limnichid larvae have asetose basal mandibular processes. At the present time, we cannot determine whether the preceding characteristics are peculiar to this species or to the genus and the subfamily. The presence of a setose basal mandibular process is not unusual in larvae of the superfamily Dryopoidea . For example, Ptilodactylidae and Elmidae have a mandibular basal setose process ( Brown 1991; Lawrence 1991).

Biological Notes. The habitat ( Fig. 8 ) is along a seashore at the base of a sandstone cliff where the waves beat only during high tide. Adults were not observed on dried rocks but were present on wet rocks during low tide along with a small staphylinid beetle and Ligia sp. (Isopoda) . The larvae presumably live in cracks and small holes of the rock, because their movements are slow and they could not be found on the surface of rocks in the field. Surfaces of the rocks were covered with pale green vegetation (Bacillariophyceae?), and we believe that the larvae live and feed on this substrate.

Figures

Figs. 1–7. Larva of Babalimnichus masamii M. Satoˆ. 1) Habitus in lateral aspect; 2) head in dorsal aspect; 3) labium and maxillae; 4) right antenna in dorsal aspect; 5) labrum in dorsal aspect; 6) mandible in ventral aspect (a) and dorsal aspect (b); 7) front (a), middle (b) and hind legs (c). Scale bar = 100 µm.

Fig. 8. Habitat of Babalimnichus masamii M. Satô in Aichi Pref.