Muelleritermes Cancello, Oliveira & Rocha

Oliveira, Danilo E., Rocha, Mauricio R. & Cancello, Eliana M., 2015, Muelleritermes: A new termite genus with two species from the Brazilian Atlantic Forest (Isoptera: Termitidae: Nasutitermitinae), Zootaxa 4012 (2), pp. 258-270 : 259-263

Muelleritermes Cancello, Oliveira & Rocha , new genus

Type-species: Muelleritermes fritzi , sp. n.

Etymology. Named in honor of the renowned naturalist Fritz Müller (1821–1897) who lived in southern Brazil and made important contributions to ecology, evolution, botany, and also termitology.

Imago: Head rounded, broad ( Fig. 1 ), with carina on dorsal surface appearing as half-moon ridge in anterior region, in frontal view forming narrower line between ocelli, as an inverted V, reaching central portion of postclypeus, delimiting a depressed area, anterior to the fontanelle ( Fig. 2 B, white arrow). In profile, carina forming head contour with anterior elevation extending from postclypeus to posterior margin of ocellus, where an almost abrupt depression occurs before posterior third part of head. Posterior margin of head capsule behind eyes semi-circular, in dorsal view. Oval spot present in front of each ocellus, and sometimes few small spots near carina. Fontanelle distinct, cross-shaped, paler than and distinct from head surface. Postclypeus moderately arched in profile, short in dorsal view, with distinct median line. Ocellus perpendicular in profile. Ocellus separated from eye by distance equal to its major diameter. Antennae with 15 articles. Pronotum broad and long, not as wide as maximum width of head with eyes. Posterior margin of pronotum not emarginate, slightly emarginate or very strongly emarginate. Lateral surfaces of forecoxae rugose ( Fig. 2 B, black arrow). Wings very long, surpassing tip of abdomen by about total length of body, surface densely covered with asteroid micrasters and also with sparse curved hairs, posterior margins covered with papillae curved toward apex. Pilosity: very hairy, with many erect bristles, and hairs of different sizes; base of posterior region, just above neck, without bristles and with only few very short hairs.

Soldier: Trimorphic. Head capsule of major soldier broad, rounded, almost square or slightly oval, without constriction behind antennae ( M. globiceps , sp. n.), occasionally very slightly constricted (some individuals in M. fritzi , sp. n.), oval or slightly oval in intermediate soldier. Head capsule of minor soldier narrower, elongate, or oval with constriction behind antennae, which is conspicuous in M. fritzi , sp. n. and less marked in M. globiceps , sp. n. Behind antennae of all soldiers are a few vestigial ommatids, and between base of nasus and base of antennae, in profile, is a kind of lens, reminiscent of a vestigial ocellus, not very clear in the figures. Mandibles with distinct, easily visible points. Nasus slightly conical in major and intermediate soldiers, cylindrical in minor soldier. Tibial spurs 2:2:2. Pilosity of soldier head consisting of short hairs oriented in different directions, denser in major soldier, less dense in intermediate soldier and sparse in minor soldier, plus some bristles that differ in size and number in the three soldier morphs (major, intermediate and minor) and in the two species.

Worker: Dimorphic, the minor worker occurs rarely. Major worker has two types of mandibles (termed narrow- and broad-gap by Fontes, 1987). Head rounded ( Fig. 3 ), antennae with 14 articles, postclypeus not inflated, fontanelle inconspicuous, anterior lobe of pronotum larger than posterior lobe, anterior margin of anterior lobe not emarginate. Head and body covered with sparse bristles and hairs. Mandibles of minor worker ( Fig. 4 A) and narrow-gap worker ( Fig. 4 B): Left mandible, apical tooth shorter than M1+2; region between apical tooth and M1+2 tooth subconcave; anterior edge of M1+2 almost twice length of anterior edge of M3; narrow-gap between M3 and molar prominence; molar tooth fully hidden by molar prominence; molar prominence with conspicuous ridges. Right mandible, apical tooth approximately as long as M1 (slightly smaller in short-gap worker); anterior edge of M2 reduced, about one-third of M1 length; molar plate with conspicuous ridges. Mandibles of broad-gap worker ( Fig. 4 C): Left mandible, apical tooth larger than M1+2; angle between base of apical tooth and M1+2 tooth more acute than in narrow-gap mandible; anterior edge of M3 half length of M1+2; large gap between M3 and molar prominence; molar tooth fully hidden by molar prominence; molar prominence with conspicuous ridges. Right mandible, apical tooth approximately equal in length to M1; anterior margin of M2 reduced, one-third length of M1; molar plate with conspicuous ridges. Worker digestive tube ( Figs. 5–7 ): Crop well developed, covered with finely pectinate scales ( Fig. 5 B). Gizzard of generalized type, narrowing at end, forming 'neck' ( Fig. 5 A). Mixed segment about twice as long as wide. Malpighian tubules in two pairs, well separated from each other, attached at edge of mesenteron, all curved toward P1. P1 short, at left side of abdomen ( Fig. 6 A and D). P2 curved ( Fig. 7 A), also on left side, after dorsal loop of mesenteron ( Fig. 6 C). Enteric valve with two rings, each composed of six weakly sclerotized plates, covered with spines ( Fig. 7 B). First ring with elongated plates, covered with tiny, isolated spines. Second ring with three elliptical plates alternating with three cylindrical ones, all plates more heavily sclerotized and with larger spines than plates of first ring. P3 large, with striated protuberance around P2 ( Fig. 6 C and E, arrow).

Geographical distribution. This genus has been found only in the southern Atlantic Forest ( Fig. 8 ).

Comparisons with other Nasutitermitinae genera. Muelleritermes gen. nov. can be easily distinguished from other members of Nasutitermitinae , except Velocitermes and Diversitermes , by the presence of three types of soldiers and a pair of vestigial ocelli (described below) on the soldier's head. The main characteristics that distinguish these two genera from Muelleritermes gen. nov. are: Diversitermes : soldiers with head densely covered with microscopic hairs; third segment of antennae longer than fourth; intermediate soldier with constriction behind antennae; nasus cylindrical, with narrow base; workers with mixed segment proportionally shorter; Malpighian tubules in two pairs attached closely to each other, frequently attached to nodule of mesenteron; P3 with protuberance separated from rest of segment by conspicuous constriction. Velocit ermes: heads of major and intermediate soldiers with constriction behind antennae; intermediate soldier with cylindrical nasus; workers with mixed segment proportionally shorter; P4 crossing mesenteron at lateral side of abdomen.

Phylogenetic position. Muelleritermes gen. nov. shares many characteristics with Velocitermes and Diversitermes (see above) and most likely is phylogenetically related to them. The gut morphology is almost identical to Ngauratermes, particularly in the shape of the mixed segment and the attachment of the Malpighian tubules. The presence of three types of soldiers; the shape of the head of the intermediate soldier, and the pilosity of the head, along with the differences listed above, strongly support Muelleritermes as a new genus included in the “ Velocitermes group” i.e. Velocitermes , Diversitermes and Ngauratermes. The phylogenetic relationships within this group remain uncertain, and are under study by the first author

Remarks. The species of Muelleriterme s, gen. nov. seem to feed on very rotten wood. They do not build a nest, but carve galleries in decayed fallen logs. The presence of ommatids on the soldier's head is reported for the first time in a genus of Nasutitermitinae . This was formerly known only in basal groups such as Kalotermitidae , Hodotermitidae , Stolotermitidae and Serritermes . The vestigial ocelli between the nasus and antennae are also present in most species of Velocitermes and Diversitermes . Whether these ommatids and the vestigial ocelli have a specific function is unknown.

Figures

FIGURE 1. Imagoes of Muelleritermes fritzi, sp. n. Head in dorsal view and in profile: A, C: male; B, D: female.

FIGURE 2. Imago of Muelleritermes fritzi, sp. n. A: thorax in dorsal view; B: head in frontal view; C: micrasters on wing surface; D: papillae on wing edge. White arrow: carina; black arrow: rough edge of coxa.

FIGURE 3. Workers of Muelleritermes, new genus, head in dorsal view and in profile. A, B: major worker of M. fritzi, sp. n.; C, D: minor worker of M. fritzi, sp. n.; E, F: major worker of M. globiceps, sp. n.; G, H: minor worker of M. globiceps, sp. n.

FIGURE 4. Mandibles of workers of Muelleritermes fritzi, sp. n. A: minor worker; B: major worker with narrow gap; C: major worker with broad gap.

FIGURE 5. Worker of Muelleritermes fritzi, sp. n. A: gizzard; B: pectinate scales of crop (barely visible at top of 5 A).

FIGURE 6. Digestive tube of worker of Muelleritermes fritzi, sp. n. A: ventral view; B: right view; C: dorsal view; D: left view; E, F: P 3; G: mixed segment; H: insertion of Malpighian tubules. Black arrow: striated protuberance of P 3.

FIGURE 7. Enteric valve of Muelleritermes fritzi, sp. n. A: curvature of P 2; B: enteric valve opened.

FIGURE 8. Collection localities of Muelleritermes, new genus.