Ngauratermes, Constantino, Reginaldo & Acioli, Agno N. S., 2009

Constantino, Reginaldo & Acioli, Agno N. S., 2009, Ngauratermes arue, new genus and species of nasute termite (Isoptera: Termitidae) from the Amazon, Zootaxa 2239, pp. 22-30 : 23-26

Ngauratermes , new genus

Type-species: Ngauratermes arue , sp.n.

Etymology: from the Ticuna language “ngau'ra” = litter, and the Latin “termes” = termite, meaning termite from the litter or litter inhabiting termite. We suggest the pronunciation “engaura-”, with the “au” similar to “ow” in the word “now”.

Imago. Unknown.

Soldier. Dimorphic ( Figs. 1 A-D). Mandibles with distinct points. Antennae with 13 articles. Nasus narrow at base, nearly cylindrical. Head capsule of major soldier broad and with a slight constriction behind antennae; sides converging towards front. Head capsule of minor soldier narrow, with a conspicuous constriction behind antennae. Tibial spurs 2:2:2.

Worker 1 (narrow gap) ․ Head capsule rounded. Fontanelle spot indistinct. Antenna with 14 articles; and fourth antennal articles very short and unsclerotized ( Fig. 2 A). Mandibles with short apical tooth ( Figs. 2 C- D). Left mandible: cutting edge between M1 and M3 slightly convex; M4 hidden behind molar prominence in dorsal view; gap between M3 and molar prominence ( Fig. 2 C); left mandible index 0.35. Right mandible: M1 larger than A; M2 shorter than A; molar plate broad, concave and with weakly developed ridges ( Fig. 1 G). Crop relatively large ( Figs. 3 A-D). Gizzard moderately developed ( Fig. 4 A); ratio of columnar belt to width of head 0.1; pulvilli I longer than the columns; about 30% of the column length covered by pulvilli I. Mixed segment short and tubular, with a single mesenteric tongue on the external face. Malpighian tubules dilated in their proximal part, each attached separately at the junction of mesenteron to proctodeum. P1 simple and tubular, without a terminal loop. Enteric valve conical and curved, located posteriorly and inserted into P3 at the dorsal left side ( Fig. 3 A and 3G). Armature weakly sclerotized, with two distinct rings of spines ( Figs. 4 B- D). The anterior ring is much longer and lacks distinct plates; it has numerous tiny spines oriented posteriorly, arranged in three areas. The posterior ring is short, located near the junction with P3 and is composed of six relatively distinct plates, three long and narrow plates alternating with three short and wide plates; both types of plates are covered with small conical spines, larger than those in the anterior ring. P3 piriform, with a constriction in its posterior part.

Worker 2 (broad gap). Worker type 2 seems to occur in very low proportion (only 6 among 103 workers in the type series of N. arue ) and can be distinguished by the color of the head capsule, which is darker posteriorly, more slender body, left mandible with broad gap between M3and molar prominence ( Fig. 2 D), mandibles more elongate and with shorter marginal teeth, left mandible index 0.32, third antennal article as long as second and more sclerotized ( Fig. 2 A), and slightly longer legs. Worker types 1 and 2 overlap in size ( Fig. 5 A) and cannot be classified as major and minor.

Comparisons. Ngauratermes shares many similarities with the group formed by Tenuirostritermes , Diversitermes , and Velocitermes , especially the last two genera. (1987) provides a detailed description of the gut of representatives of these genera and Roisin et al. (1996) presents a description of the gut and enteric valve of Velocitermes barrocoloradensis . Velocitermes . This genus currently includes 10 species and occurs in Central and South America. Most species of Velocitermes occur only in savannas and feed on grass litter. They are well sclerotized, have long legs and antennae, and move rapidly. Soldiers may be di- or trimorphic, and workers are dimorphic. All soldiers have a distinct constriction behind antennae. In Velocitermes , the Malpighian tubules are attached in two pairs directly to the mesenteron or at the mesentero-proctodeal junction. Worker mandibles have narrower molar plate with more conspicuous ridges ( Fontes 1987). Diversitermes . This genus currently includes three South American species, but D. aporeticus seems to be incorrectly placed and is probably a Velocitermes species. D. castaniceps and D. diversimiles have trimorphic soldiers ( Constantino 2002, Figures 91-94), and dimorphic workers. The head of their major soldier is oval and not constricted. They are more sclerotized than Ngauratermes and have longer legs and antennae. In Diversitermes , the Malpighian tubules are not dilated in their proximal part and are attached in two pairs to a small nodule at the junction of the mesenteron to the proctodeum ( Fontes 1987). Also, in Diversitermes the enteric valve is inserted into a cylindrical pouch of P3, which is absent in both Ve l o c i t e r m e s and Ngauratermes . Tenuirostritermes . This genus includes four species which occur in North and Central America. It is also present in northern Venezuela (R. Scheffrahn, pers. comm.), but does not seem to occur in the Amazon or other parts of South America. Soldiers of Tenuirostritermes are monomorphic, with a strongly constricted head, long legs and antennae. The gut is similar to that of Diversitermes and Velocitermes ( Fontes 1987) , but has a longer mixed segment and the Malpighian tubules are inserted in two separate pairs. Antillitermes , Parvitermes , Caribitermes , and Obtusitermes . Soldiers and workers of several species in this group are similar to Ngauratermes in size and external morphology. In these genera, the first proctodeal segment forms a distinct, very elongate and narrow loop extending to the right and ventral side of abdomen; their crop is small and the mixed segment is very long ( Roisin et al. 1996). Soldiers of Antillitermes and Obtusitermes have antenna with less than 13 articles and mandibles without points. Soldiers of Caribitermes are monomorphic and their head is not constricted behind antennae. Parvitermes is more variable and some species have dimorphic soldiers and external morphology rather similar to Ngauratermes . None of these genera occur in the Amazon. Parvitermes bacchanalis is a special case, because it clearly does not belong in Parvitermes ( Fontes 1987; Roisin et al. 1996). The gut morphology of P. bacchanalis is distinct, with a long P1 rolled around P3 and forming a loop between the mixed segment and P3, with P2 attached to P3 from a dorso-anterior position. Soldiers of P. bacchanalis have only microscopic hairs on the head. This species occurs only in the Cerrado (savanna) of central Brazil. Triangularitermes . The major soldier of Ngauratermes resembles the soldier of Triangularitermes triangulariceps , which has similar size, color, shape of head capsule, antenna with 13 articles, mandibles with distinct points and occur in the same region. The monomorphic soldier of T. triangulariceps has a more conical nasus, has longer legs and antennae, and lacks the numerous short hairs on the head ( Mathews 1977). The mixed segment of Triangularitermes is longer, and the Malpighian tubules are attached grouped in the same point. The end of P1 forms a short loop dorsally and the enteric valve has two rings of spines of similar length ( Fig. 6 F).

Remarks. The enteric valve armature of Ngauratermes is weakly sclerotized and relatively difficult to dissect and examine, but it does have a distinctive armature with two rings of spine areas, a pattern common to several other genera of Nasutitermitinae ( Noirot 2001) including Nasutitermes . The relative size and degree of sclerotization of each of these two rings varies among genera and species ( Fig. 6 ; other examples in Sands 1998, p. 495). In the generalized type, both rings have six spine areas; the anterior ring is less sclerotized and has numerous tiny spines, while the posterior ring is formed of more conspicuous plates (cushions) with larger spines. The length of each ring is variable, and the posterior one is usually shorter. In several species the armature is reduced. In Nasutitermes corniger , for instance, the posterior ring is very short, with only three small cushions ( Fig. 6 A), while in Constrictotermes cyphergaster the posterior ring is well developed ( Fig. 6 G) and the anterior one is vestigial (a few very small spines are present, but are not visible in Fig. 6 G).

Figures

FIGURES 1. Ngauratermes arue, new species. A, head of major soldier in dorsal view; B, same in profile; C, head of minor soldier in dorsal view; D, same in profile; E, head of worker (type 1) in dorsal view; F, same in profile; G, molar plate of right worker mandible (type 1).

FIGURES 2. Ngauratermes arue, new species. A, Antenna of major soldier and workers; B, foreleg of worker type 1; C, mandibles of worker type 1; D, mandibles of worker type 2 (a little worn).

FIGURES 3. Ngauratermes arue, new species. Gut morphology of worker. A, gut in situ, in dorsal view; B, left view; C, ventral view; D, right view; E-F, mixed segment and insertion of Mapighian tubules; G, schematic representation of a posterior view of a cross section of the end of abdomen (rectum removed) showing the position of the enteric valve. P 1, first proctodeal segment; P 2, enteric valve; P 3, third proctodeal segment or paunch.

FIGURES 4. Ngauratermes arue, new species. A, gizzard armature; B, enteric valve showing the two rings of spines; C, opened valve showing armature; D, detail of the two types of plates of the posterior ring. The arrows are aligned with the axis of the valve and orientated posteriorly (from P 2 to P 3).

FIGURES 5. Ngauratermes arue, new species. A, scatterplot showing morphometric variation in the two worker types; B, scatterplot showing morphometric variation in the two soldier types.

FIGURES 6. Enteric valve armature of other genera of Neotropical Nasutitermitinae. A, Nasutitermes corniger; B, Nasutitermes surinamensis; C, Diversitermes diversimiles; D, detail of the enteric valve armature of D. diversimiles, showing the two types of plates of the posterior ring; E, Triangularitermes triangulariceps; F, Velocitermes heteropterus; G, Constrictotermes cyphergaster. The arrows are aligned with the axis of the valve and orientated posteriorly (from P 2 to P 3).