Nasutitermes callimorphus Mathews, 1977

Scheffrahn, Rudolf H., Roisin, Yves, Szalanski, Allen L., Austin, James W. & Duquesne, Edouard, 2024, Expanded range of Nasutitermes callimorphus Mathews, 1977 (Isoptera: Termitidae: Nasutitermitinae), comparison with N. corniger (Motschulsky, 1855) and N. ephratae (Holmgren, 1910), and synonymy of N. dasyopsis Thorne, 1989 into N. nigriceps (Haldeman, 1854), Zootaxa 5507 (1), pp. 57-78 : 59-66

Nasutitermes callimorphus Mathews, 1977

“ N. indistinctus ” [nomen nudum] page 161, fig. 110 ( Mathews 1977) should read Nasutitermes callimorphus ( Constantino and Cancello 1999) .

IMAGO ( Fig. 1A, B ; Table 1 ). Head capsule dark sepia brown with light brown postclypeus, genae, and paler spotting at all setal insertions; fontanelle slit whitish. Only faint posterior remnants of epicranial suture visible. Compound eyes black, ocelli glossy tan. Numerous pale setae of different lengths on head capsule, pronotum, and postclypeus; few on labrum. Pronotum pale sepia brown, distinctly paler than head capsule and with pale T-shaped mark; pronotum more distinctly and more densely pimpled setal insertions than on head capsule. In lateral view, vertex and anterior occiput slightly bulging; eyes subcircular and medium sized. In dorsal view, head capsule trapezoidal; ocelli small; eyes and ocelli separated by distance about maximum diameter of ocelli. Head capsule, pronotum, and wing scales densely pilose with long setae. Antennae with 15 articles; relative length formula 2=3<4=5. In dorsal view, pronotum narrow, subtriangular; anterior margin rectate and with minute median indentation; pronotum sides distinctly convergent; anterior margin of pronotum barely elevated, elevation posteriorly delimited with short dark line on each side of T-shape mark. Pronotum posterior margin half width of anterior margin and slightly emarginate or concave. Mandible morphology typical for Nasutitermes ( Ahmad 1950) .

Comparisons

The N. callimorphus imago superficially resembles those of N. corniger ( Figs. 4A, B ) and N. ephratae ( Figs. 7A, B ). Imagos of both have very similar coloration, but N. callimorphus is distinctly smaller in most measurements, e.g., maximum head width at eyes (1.08–1.13, 1.34–1.57, and 1.31–1.40 mm; maximum pronotum width (0.74–0.85, 1.05–1.36, and 0.97–1.11 mm), and total length with wings (9.31–10.77 mm vs. 12.10–15.83 mm) and fore wing length to suture (7.58–9.04, 9.44–12.77, and 12.2–12.8 mm) for N. callimorphus , N. corniger , and N. ephratae , respectively ( Scheffrahn et al. 2005, Mathews 1977). The dorsal outline of the N. callimorphus pronotum is subtriangular ( Fig. 1A ), while in N. corniger it is more trapezoidal ( Fig. 4A ), and in N. ephratae the lateral and posterior margins are nearly evenly rounded ( Fig. 7A ). In dorsal view, the compound eyes of N. ephratae bulge upward and forward while in N. callimorphus and N. corniger the eyes project more laterally. The compound eyes of N. callimorphus are nearly round ( Fig. 1B ), while in N. corniger ( Fig. 4B ) and in N. ephratae ( Fig. 7B ) they are elliptical. Both the compound eyes and ocelli of N. ephratae are proportionally larger than the other two species. The head capsule and pronotum pilosity of the N. callimorphus imago is less dense and that of N. corniger or N. ephratae .

SOLDIER ( Fig. 2A–F , Table 2 ). The description of N. callimorphus soldier by Mathews (1977) is adequate.

Comparisons

The N. callimorphus soldier ( Fig. 2 ) superficially resembles that of the N. corniger ( Fig. 5 ) and the N. ephratae soldier ( Fig. 8 ). The N. callimorphus soldier is distinctly smaller in most measurements, e.g., head length with nasus (1.19–1.36, 1.28–1.39, 1.37–1.77, and 1.29–1.56 mm); maximum head width (0.72–0.79, 0.77–0.83, 0.82– 1.31, and 0.68–97 mm); and maximum pronotum width (0.37–0.39, 0.37–0.42, 0.44–0.65, and 0.37–0.49 mm); for N. callimorphus herein, N. callimorphus ( Mathews 1977 in italics), N. corniger ( Scheffrahn et al. 2005) , and N. ephratae ( Mathews 1977) , respectively.

The anterior pronotal lobe of the N. callimorphus soldier has only very short anterior marginal setae ( Fig. 2B ), while the anterior pronotal lobes of N. corniger ( Fig. 5B ) and N. ephratae ( Fig. 8B ) soldiers also bear much longer setae. The antennal relatively length formula of N. callimorphus is 2=3>4<5, while in N. corniger and in N. ephratae the formulae are 2<3>4<5. Both N. callimorphus ( Fig. 2C ) and N. corniger ( Fig. 5C ) soldiers have fine short setae on the tergite interiors of while in N. ephratae , setae are pronouncedly more minute ( Fig. 8C ).

The vertex of N. callimorphus in lateral view ( Fig. 2E ) is nearly straight while in N. corniger ( Fig. 5E ) and in N. ephratae ( Fig. 8E ) they have a median concavity.

WORKER ( Figs. 1C, D ). Dimorphic; major workers more common. Head capsule dark brown with broad whitish cranial sutures, with scattered medium setae. Pronotum with light brown margins, lighter interior; a row of very small setae along anterior lobe, a few long setae on both lobes. Gut configuration very similar to N. corniger ( Fontes 1998) . Enteric valve armature composed of a single basal grouping of ca. 36 scattered spines, three median quadrate patches of ca. 20–25 spines, and three anterior elongate groupings of 4–10 spines; a few additional spines scattered randomly. Major workers (mean ± S.D.) maximum head width 0.96 ± 0.032 mm; maximum pronotum width 0.48 ± 0.031 mm. Minor workers (mean ± S.D.) maximum head width 0.78 ± 0.026 mm; maximum pronotum width 0.40 ± 0.023 mm.

Comparisons

The N. callimorphus worker superficially resembles those of N. corniger ( Figs. 4C, D ) and N. ephratae ( Figs 7C, D ) but the head capsule and pronotum is darker especially in the genal region. In lateral view, the postclypeus of N. callimorphus rises as a gentle ca. 120° peak, while in the other two species, the postclypeus in bulbous and inflated. In lateral view, the pronotum of N. callimorphus has a couple of long and many minute setae on the anterior lobe while in the other species, there are more long setae and the minute setae are longer. The EVA spines of N. callimorphus workers ( Fig. 3A ) are smaller and more delicate that either N. corniger ( Fig. 6A ) or N. ephratae ( Fig. 9A ). The N. callimorphus workers are distinctly smaller in all measurements.

Distribution and biology

Nasutitermes callimorphus (suppl. Table 1 , Fig. 13A ) along with N. corniger ( Fig. 13B , Santos et al. 2017) and N. ephratae ( Fig. 13C , Scheffrahn et al. 2005, Santos et al. 2022) are among the most broadly distributed termites in the Neotropics. All are wood feeders and can be pestiferous ( Constantino 2002). Nasutitermes callimorphus is a forest species, while N. corniger and N. ephratae are found in nearly all habitats. Its preference for the forest is confirmed by the species distribution model which shows a high suitability in most of the neotropical forests ( Fig. 14 ). It lives in small colonies and nests in dead, often thin branches, including those still on living trees, an unusual habit among congeners. Colonies are also located underneath logs on the forest floor ( Fig. 3B ). Foragers behave much like N. corniger and N. ephratae with which they are usually sympatric. Nasutitermes callimorphus may be monogynous based on a single functional physogastric queen collected. Presence of mature alates in tree branch galleries on Guadeloupe at the end of May and beginning of June suggests that flights commence in the beginning of the rainy season. Nasutitermes corniger builds both epigeal and arboreal nests with a friable carton texture ( Fig. 6B ) while N. ephratae builds globous arboreal nests that are covered with a smooth skin ( Fig. 9B ). Nasutitermes nigriceps , a larger species, is found in dryer coastal zones of Central America, northern South America, and parts of the West Indies ( Fig. 13D ).

Genetic relationships

Based on the maximum parsimony analysis of the 16S rRNA sequences (length = 248, CI = 0.774) N. callimorphus formed a distinct clade. With maximum likelihood analysis ( Fig. 11 ), N. callimorphus is sister species of N. intermedius (whose transfer to Cortaritermes was proposed by Cuezzo et al. 2015, but not supported by phylogenetic evidence) and within the same clade as N. corniger , N. coxipoensis , N. ephratae , and N. globiceps ( Fig. 11 ). With the COII genetic marker, the maximum likelihood analysis revealed that all of the N. callimorphus samples formed a distinct clade, that was a sister group to N. intermedius ( Fig. 12 ). This clade fell within a group consisting of N. corniger , N. ephratae , N. coxipoensis , and N. globiceps . Similarly, Roy et al. (2014), using the combined sequences of 16S and COII genes, comes to the same conclusion.

Figures

FIGURE 1. Nasutitermes callimorphus from Guadeloupe (GU499). Imago head (dorsal A, lateral B) and major worker head (dorsal C, lateral D).

FIGURE 2. Nasutitermes callimorphus soldier from Peru (PU361). Habitus (A); lateral view of pronotum (B); tergites (C); and dorsal, lateral, and ventral views of head capsule (D, E, and F, respectively).

FIGURE 3. Nasutitermes callimorphus worker enteric valve armature (arrow: direction of food flow; A) and field habitus of foragers (B).

FIGURE 4. Nasutitermes corniger from Grenada (GR223). Imago head (dorsal A, lateral B) and major worker head (dorsal C, lateral D).

FIGURE 5. Nasutitermes corniger soldier from Grenada (GR223). Habitus (A); lateral view of pronotum (B); tergites (C); and dorsal, lateral, and ventral views of head capsule (D, E, and F, respectively).

FIGURE 6. Nasutitermes corniger worker enteric valve armature (A) and nest (B).

FIGURE 7. Nasutitermes ephratae from Guadeloupe (GU873). Imago head (dorsal A, lateral B) and major worker head (dorsal C, lateral D).

FIGURE 8. Nasutitermes ephratae soldier from Bolivia (BO181). Habitus (A); lateral view of pronotum (B); tergites (C); and dorsal, lateral, and ventral views of head capsule (D, E, and F, respectively).

FIGURE 9. Nasutitermes ephratae worker enteric valve armature (A) and nest (B).

FIGURE 11. Phylogenetic tree (ln L = -2792.71626) of Nasutitermes taxa, based on 16S rRNA sequences constructed using the PhyML maximum likelihood method with 1000 bootstrap replications.

FIGURE 12. Maximum likelihood tree of the COII mtDNA gene subjected to sequencing, -ln L = 9946.57113. Bootstrap values ≥ 50% from PhyML analyses are shown. Thickened branches indicate Bayesian posterior probabilities ≥ 75%. Bootstrap values ≥ 50% from PhyML analyses are shown.

FIGURE 13. Distribution of Nasutitermes spp. from the University of Florida Termite Collection (red dots).A, N. callimorphus (blue dots from literature); B, N. corniger; C, N. ephratae; and D, N. nigriceps (orange dots N. daysiopsis syn. nov. presumed localities).

FIGURE 14. Potential current suitability of N. callimorphus according to the species distribution modeling.

Tables

TABLE 2. MEASUREMENTS OF NASUTITERMES CALLIMORPHUS SOLDIER.

Measurement in mm (n = 18*)	Range	Mean ± S.D.
Head length with nasus	1.19–1.3	1.29 ± 0.050
Head length without nasus	0.75–0.85	0.82 ± 0.031
Head width, maximum	0.72–0.79	0.76 ± 0.022
Nasus width at base	0.20–0.25	0.22 ± 0.018
Nasus width at middle	0.10–0.13	0.11 ± 0.010
Nasus length	0.43–0.51	0.48 ± 0.022
Head height, without postmentum	0.49–0.57	0.53 ± 0.027
Pronotum, maximum width	0.37–0.39	0.38 ± 0.0096
Pronotum, maximum length	0.11–0.15	0.13 ± 0.0092
Hind tibia length	0.82–0.92	0.87 ± 0.025
Total length	3.18–3.77	3.47 ± 0.17

*From eleven localities.