A new species of Acorhinotermes Emerson, 1949 (Blattodea, Isoptera, Rhinotermitidae) from Colombia, with a key to Neotropical Rhinotermitinae species based on minor soldiers

Abstract Acorhinotermes Emerson, 1949 is the only Neotropical Rhinotermitine genus with no major soldier. Herein Acorhinotermes claritae Castro & Scheffrahn, sp. nov. is described based on minor soldiers and an alate nymph collected in a secondary rain forest in the Colombian Amazon. The minor soldier of A. claritae Castro & Scheffrahn, sp. nov. has longer mandibular points and it is comparatively smaller than A. subfusciceps. An illustrated key to the minor soldiers of the Neotropical species of Rhinotermitinae is presented.

Acorhinotermes subfusciceps was originally described within the genus Rhinotermes (Emerson 1925;Snyder 1949). Emerson in Snyder (1949) transferred Rhinotermes subfusciceps to a new genus, Acorhinotermes, straightening the absence of the major soldier as a diagnostic characteristic of the genus.
In this paper, we describe a new species Acorhinotermes claritae sp. nov. based on characters from the minor soldier and alate nymph. We provide as well as an illustrated key for the Neotropical Rhinotermitinae based on the minor soldier caste, which would be very helpful when major soldiers or imagoes are not represented in the collected samples.

Materials and methods
Specimens of Acorhinotermes claritae sp. nov. were collected in trucks of dead trees with aspirators, at weet season (July 12-19, 2018), in the southern state of Amazonas, Colombia, and preserved in 95% ethanol. The holotype and paratypes are deposited in the "Colección de Artrópodos Terrestres de la Amazonía Colombiana", SINCHI Amazon Institute of Scientific Research, Leticia, Amazonas, Colombia (CATAC). Paratypes are also deposited in the Termite Collection, Fort Lauderdale Research and Education Center, University of Florida, Davie, Florida, United States of America (UF).
Morphological characters used for the alate nymph and minor soldier follows Roonwal (1970). Microphotographs were taken as multi-layer montages using a Leica M205C stereomicroscope controlled by Leica Application Suite version 3 software. Preserved specimens were suspended in a pool of Purell Hand Sanitizer to position the specimens on a transparent Petri dish background. Diagnosis. Minor soldier head with concave lateral margins forming a posterior constriction, with prominent mandibular points extend beyond the fontanelle.

Acorhinotermes claritae
Description. Alate nymph. (Fig. 1A, B) Head capsule yellowish-brown, widely oval with numerous long bristles. Antennae with 20 articles, 2<3=4. Dorsum of body concolorous with head capsule. Compound eyes subcircular, eye margins wide and broadly separated from antennal sockets. Ocelli of small size, oval, well separated from eyes. Clypeus linguiform, not buttressed by frontal projection. Pronotum margin with numerous long bristles; rounded lateral margins. Mandibles with M1 more prominent than apical teeth. Right mandible with M1 more projected than left mandible. Left mandible with M2 projected to half the length of M1, M2 and M3 forms an obtuse angle, M3 and molar tooth projected at same distance.
Measurements (mm) for a single alate nymph: head length with labrum 1.27, head length to postclypeus 1.46, maximum width of the head with eyes 1.39, width of head without eyes 1.21, diameter of eye 0.25, ocellus diameter 0.08, length of pronotum 0.78, width of pronotum 1.36, total body-length without wings 6.81.
Comparisons. Acorhinotermes claritae sp. nov. has more abundant bristles in lateral view. The ocelli and eyes are smaller than the A. subfusciceps imago, and the clypeal projection projects more acutely in A. claritae sp. nov. and it is not buttressed by a frontal projection as in A. subfusciceps (Fig. 1C).
Comparisons. Acorhinotermes claritae sp. nov. is smaller and has longer mandibular points than A. subfusciceps. In profile, the dorsa of the occiput, vertex, and labrum of A. claritae sp. nov. form a nearly straight line, while in A. subfusciceps this profile

Figure 3. Minor soldiers of Neotropical Rhinotermitinae deposited in UF and CATAC termite collections A-C Acorhinotermes subfusciceps D-F Dolichorhinotermes longidens G-I Dolichorhinotermes lanciarius.
forms an obtuse angle (Fig. 3A, B). All minor soldiers of Dolichorhinotermes and Rhinotermes have the labrum tip bifurcated (forked or divided into two parts or branches), and it is much more bilobed in A. subfusciceps than in A. claritae sp. nov. Biological notes. Acorhinotermes claritae sp. nov. was collected in a secondary rain forest near the Tacana river, close to a "chagra" (indigenous agricultural production system). During the wet season, these areas are in flood zones. The colonies were found in trunks of dead trees and in big dry branches on the ground. One particular colony of this species was found in a same dead branch together with Heterotermes tenuis (Hagen, 1858) and Cylindrotermes parvignatus Emerson, 1949, and another colony with Silvestritermes gnomus (Constantino, 1991). Acorhinotermes claritae sp. nov. was collected in a unique locality near the city of Leticia, although we did surveys in other two sites of a radius no greater than 15 km, it was not collected.
Distribution. The genus Acorhinotermes is distributed in the Amazon basin, Guiana shield and Caatinga (Fig. 5). A. claritae sp. nov. is restricted to the Amazon basin.
Etymology. The species is named in honor of Dr. Clara (Clarita) Peña-Venegas, who has supported and promoted the knowledge and inventories of termites and other terrestrial arthropods from the Colombian Amazon in the SINCHI Institute. Mandibular points extend beyond the fontanelle (Fig. 2A) .... A. claritae sp. nov. -Mandibular points do not extend beyond the fontanelle (Fig. 3A-C)  Mandibles points reduced to minute points on basal lobes (Fig. 3F, I)  Smaller species: head length less than 1.10 mm. Panama (Fig. 3D-F)  Head length to labrum tip 1.70-1.93 mm (Fig. 4D-F) (Snyder, 1926) and Dolichorhinotermes neli Ensaf & Betsch, 2002 were not included in this key because we suspect they are junior synonyms of Dolichorhinotermes longilabius (Emerson, 1924). *** These species cannot be separated only with the minor soldier. It is necessary the imago or the major soldier caste.

Discussion
In our Colombian survey, about 102 minor soldiers were collected without a single major soldier reinforces our belief that the latter caste is absent from A. claritae sp. nov. Among genera of the subfamily Rhinotermitinae, Dolichorhinotermes has been the most common in the Amazon region surveys, followed by Rhinotermes and then Acorhinotermes (Castro unpubl. data;Constantino 1991;de Souza and Brown 1994;Palin et al. 2011). However, R. marginalis is found in the West Indies while D. longilabius has not been reported from there, with the exception of the islands of Trinidad and Tobago where the latter species is common and the former has not been collected (Scheffrahn unpubl. data). A. claritae sp. nov. is the first record for the genus in Colombia.
In the key to genera of Neotropical termites, Constantino (2002) differentiated Dolichorhinotermes minor soldiers from Rhinotermes minor soldiers by the length of the head to the tip of the labrum, less than 1.2 mm, but D. tenebrosus and D. lanciarius measures greater than 1.2 mm. To differentiate these genera, the major soldier or imago caste is preferred. Major soldiers of Dolichorhinotermes have a narrow long labrum reaching near tips of mandibles while the major soldiers of Rhinotermes have a short wide labrum that extends no more than half the length of the mandibles when extended. Also, the known imagos of Dolichorhinotermes head width range is 1.18-1.29 mm while the Rhinotermes imago head width range is 1.90-2.18 mm.