Parvitermes (Isoptera, Termitidae, Nasutitermitinae) in Central America: Two new termite species and reassignment of Nasutitermes mexicanus

Abstract The termite genus Parvitermes is now recognized on the Central American mainland to include Parvitermes mexicanus, new combination (previously in Nasutitermes) and two new species, Parvitermes mesoamericanus sp. n. and Parvitermes yucatanus sp. n., herein described from soldiers and workers. These three species, nine West Indian Parvitermes, and Antillitermes subtilis all share characteristic enteric valve spines that orientate against intestinal flow. All species are subterranean nesters and cellulose feeders. Evidence is mounting that generic-level endemicity may be completely absent among the West Indian nasutitermitine fauna and that its origins stem from Central America.

Remarks. The nomenclatural summary for Parvitermes is provided by Krishna et al. (2013). The generic redescription of Parvitermes by Roisin et al. (1996) is relevant to all three Parvitermes species described herein with the exception that P. mexicanus comb. n. has a shorter first proctodeal segment (P1) compared to all others.
Diagnosis. The spine arrangement and counter-current orientation of the Parvitermes enteric valve armature (EVA), with the exception of Antillitermes, is unique among all termite genera. In addition to Parvitermes, only three other nasutitermitine genera are found from Mexico to Nicaragua, including Nasutitermes, Subulitermes, and Tenuirostritermes (Atlantitermes from Nicaragua in Scheffrahn et al. (2005) is an error). Compared to mainland Parvitermes, head capsules of Nasutitermes soldiers are larger and darker (with the exception of N. glabritergus Snyder & Emerson, 1949 from Honduras, unpubl. record), those of Subulitermes are much smaller with much narrower cylindrical nasi, and the head capsules of Tenuirostritermes are very constricted near their middle.
Workers and soldiers. The EVA arises within the second proctodeal segment (P2) which forms a swelling at the terminus of a very long (shorter and thicker in P. mexicanus), U-shaped P1. The P2 constricts somewhat at its attachment near the dorsal surface of the third proctodeal segment (P3 or paunch) to form a pear-shaped segment (Fig. 1A). The posterior EV ring (sensu Noirot 2001) of both workers and soldiers is uniquely composed of three keel-shaped pads covered with about 7-15 long spines directed into the P2 lumen (Fig. 1B). The spines are curved or angled counter to the direction of the food flow. The spiny pads are separated with or without additional patches of tiny conical teeth (Figs 1C,2). In preserved specimens, the Parvitermes spines of each pad are imbedded into a congealed pellet of presumed bacterial cells (Fig. 1C). (Light, 1933), comb. n. Nickle & Collins, 1988 (soldier Fig. 2B, 3A, B). Monomorphic; however some rare divergent size morphs reported by Light 1933. Head capsule and pronotum light orange-brown; nasus darker. In dorsal view, cephalic gland duct partially or completely visible from nasus to reservoir. Many small and a few longer setae scattered on head; setae on nasus very small and numerous.

Nasutitermes mexicanus
In dorsal view, head capsule outline, without nasus, subtrapazoidal; nasus about 2/3 as long as rest of head capsule; head capsule slightly constricted behind antennal sockets; widest at posterior 1/3. In lateral view, vertex with slight concavities near midpoint; second slight concavity at base of nasus; plane of vertex parallel with ventral margin of head capsule. In dorsal view nasus is narrowly conical, about twice its width at base compared to midpoint. In lateral view nasus narrowly conical; angled ca. 5°above plane of vertex. Mandibles without points. Antennal with 13 articles (1>2<3>4). Hind tibia longer than head width. Pronotum with scattered microscopic setae (0.03 mm); anterior lobe evenly convex and ca. 90° from plane of posterior lobe, posterior lobe more blunt. Each tergite with 3-4 long (0.1 mm) setae and dozens of microscopic (0.03 mm) setae. EVA consists of three irregular rows of sharp, narrow, and down-curved spines; a few small scale-like spines in the anterior ring.
Worker (Table 2, Figs 2A, 4A, 5A, 6A). Monomorphic. Head capsule very pale yellow with two slightly darker yellowish-orange dorso-lateral patches; pronotum very pale yellow; body, antennae, and legs hyaline. Antennal with 12 articles. Postclypeus considerably inflated in lateral view; scattered short and medium setae on head capsule. Abdomen with many short and a few scattered longer setae. Mandibles with about eight ridges on molar plate, molar plate with distinct dorsal notch; apical and first marginal teeth of similar shape and projection; third marginal smaller, separated from first by slightly concave cutting edge. Gut with P1 U-shaped turn near midpoint, bottom of turn extending only to dorso-lateral aspect of abdomen. EVA consists of three irregular rows of about 10-12 sharp, narrow, and down-curved spines; anterior ring with three patches of small scale-like spines.
Distribution. Tropical Pacific slope of Mexico (Fig. 7). Imago. Unknown. Soldier (Table 3, Figs 2D, 3CD, 8). Monomorphic. Head capsule and pronotum light orange-brown; nasus darker. In dorsal view, cephalic gland duct partially or completely visible from nasus to reservoir. Many small, some medium, and a few longer setae scattered on head; setae on nasus small and numerous. In dorsal view, head capsule outline, without nasus, ovoid; nasus about 2/3 as long as rest of head capsule; head capsule barely constricted behind antennal sockets; widest in middle. In lateral view, vertex nearly in a flat plane; vertex and ventral margin of head capsule converge to front. In dorsal view nasus is narrowly conical, about thrice its width at base compared to midpoint; In lateral view nasus conical; projecting directly anterior below plane of vertex. Mandibles with short, very narrow, points. Antennal with 12 articles (1>2<3=4). Hind tibia about as long as or shorter than maximum head width. Pronotum with scattered microscopic setae (0.05 mm); anterior lobe evenly convex and ca. 90° from plane of posterior lobe, posterior lobe more blunt. Each tergite with 3-4 long (0.13 mm) setae and dozens of microscopic (0.05 mm) setae. EVA consists of three irregular rows of about 8-12 long subtriangulate, and very slightly down-curved spines; a few small scale-like spines in the anterior ring.
Worker (Table 4, Figs 2C, 4B, 5B, 6B, 8). Monomorphic. Head capsule very pale yellow with two slightly darker yellowish-orange dorso-lateral patches; pronotum very pale yellow; body, antennae, and legs hyaline. Antennal with 12-13 articles. Postclypeus considerably inflated in lateral view; scattered short, medium, and a few longer setae on head capsule. Abdomen with many short and longer setae. Mandibles with about eight ridges on molar plate, molar plate with slight dorsal notch; apical and first marginal teeth of similar shape and projection; third marginal smaller, separated from first by slightly emarginate cutting edge. Gut with very long P1; U-shaped turn near midpoint, bottom of turn extending to ventro-lateral aspect of abdomen. EVA consists of three irregular rows of about 8-12 long subtriangulate, and very slightly downcurved spines; three patches with small scale-like spines in the anterior ring.
Etymology and distribution. Named for Middle America which encompasses Guatemala, Honduras, and Nicaragua; the known range of this termite. The distribution habitat of P. mesoamericanus (Fig. 7) is more xeric than adjacent regions lacking this termite.  Comparisons. The soldier of P. mesoamericanus has the nasus directed forward, the head capsule widest in the middle, a few scattered long setae on the vertex, and points on the mandibular stubs while in P. mexicanus, the nasus is slightly upturned, the head is widest in the posterior third, the vertex lacks scattered long setae, and the mandibular stubs have points. The worker of P. mesoamericanus has a much longer and more ventrally positioned P1, stouter and less curved EVA spines, and longer setae on the vertex, while in P. mexicanus the P1 is shorter and more dorsal, the EVA spines are thinner and more curved, and the setae on the vertex are shorter. The P. mesoamericanus worker is proportionally smaller to its soldier as compared P. mexicanus. Both castes of P. mexicanus have longer hind tibia than P. mesoamericanus. Alate. Unknown. Soldier. (Table 5, Figs 2F, 3E, F). In all respects, similar to P. mesoamericanus except for the following: In dorsal view nasus conical, about 1.6x its width at base compared to midpoint; in lateral view nasus broadly conical. Mandibles with short, very narrow, points. Antennal with 11-12 articles (1>2<3=4). Hind tibia usually shorter than maximum head width. Pronotum with a few longer setae (0.10 mm) along margin of anterior lobe.

Parvitermes yucatanus
Worker. (Table 6, Figs 2E, 4C, 5C, 6C). In all respects, similar to P. mesoamericanus except for the following: Mandibles with about seven ridges on molar plate, mo-    lar plate without dorsal notch; apical and first marginal teeth of similar shape and projection; third marginal smaller, separated from first by slightly concave cutting edge. EVA consists of three irregular rows of about 7-12 long, narrow, subtriangulate, and slightly down-curved spines. Etymology and distribution. Named for the Yucatan Peninsula which encompasses Belize, Mexico, and Guatemala; the known range of P. yucatanus (Fig. 7). This region has a pronounced dry winter season.
Comparisons. The soldiers of P. yucatanus and P. mesoamericanus are very similar with the following exception: the nasus of P. yucatanus, in lateral view, is more conical and broader at the base than that of P. mesoamericanus. The workers of P. yucatanus and P. mesoamericanus are indistinguishable. The distributions of P. yucatanus and P. mesoamericanus appear to be allopatric (Fig. 7) with the latter species occupying a more arid zone.
Biology. The Central American Parvitermes are wood-surface feeders. They typically attack wood in contact with the ground where they encase their surroundings with dark carton material (Fig. 8) reminiscent of Amitermes and build narrow foraging galleries to above-ground feeding sites (Light 1933, Weesner 1970 for P. mexicanus). Colonies nest in the soil underneath rocks and logs where brood and larvae have been found in weak cells of thin dark carton. In the West Indies, Parvitermes are often col- lected in hollowed-out stems of woody herbaceous plants (P. brooksi and P. wolcotti). In the arid lands of the Dominican Republic, P. flaveolus attacks wooden fence posts, and after rains, will feed on dried grass bunches that they cover with a thin arcade of soil.

Discussion
The current study reveals that Parvitermes is no longer a genus exclusive to the West Indies  but has a widespread mainland complement of three species. This leaves only the monospecific genera Antillitermes and Caribitermes as the remaining endemics of all termite genera in the West Indies (excluding the continental islands of Trinidad and Tobago). The gestalt of the Antillitermes subtilis EVA closely resembles that of Parvitermes s. str.  and suggests that the EVA is a mainland synapomorphy of both genera. Antillitermes subtilis may very well be a species of Parvitermes. Caribitermes discolor may also have a mainland lineage as it resembles an undescribed species from Panama (PN1315, Scheffrahn unpubl.). Therefore, it is quite possible, with the exception of the relict Constrictotermes guantanamensis from Cuba (Krěcěk et al. 1996), that all West Indian termites share congeneric species on the Central American mainland and that the West Indian fauna arose from Pleistocene/Miocene (Krishna and Grimaldi 2009) overwater dispersal events from Central America (Darlington 1938, Hedges 1996 or the more recent late Pleistocene land connections (Scheffrahn et al. 2006).