Research Article |
Corresponding author: Daniel Castro ( danielkaz80@gmail.com ) Academic editor: Fred Legendre
© 2020 Daniel Castro, Joice P. Constantini, Rudolf H. Scheffrahn, Tiago F. Carrijo, Eliana M. Cancello.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Castro D, Constantini JP, Scheffrahn RH, Carrijo TF, Cancello EM (2020) Rustitermes boteroi, a new genus and species of soldierless termites (Blattodea, Isoptera, Apicotermitinae) from South America. ZooKeys 922: 35-49. https://doi.org/10.3897/zookeys.922.47347
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We present the description of a new genus and species of soldierless termites from South America. Rustitermes boteroi Constantini, Castro & Scheffrahn, gen. et sp. nov. can be identified by the morphology of the enteric valve, with six slightly asymmetric cushions, each one forming a central pouch made of scales smaller than those between the cushions. The new genus features two characteristic rows of thick bristles on the interior margin of the fore tibia, and is supported by COI molecular sequence data. This species is distributed from Tobago to northern Argentina.
Neotropics, enteric valve, soil-feeder, barcode sequence
Soil-feeding termites represent a large part of the termite fauna in Neotropical ecosystems (
The Apicotermitinae subfamily was first proposed by
The taxonomic work of
Taxonomic study of the worker caste has been underwhelming in the Neotropical Region (
Herein we describe Rustitermes boteroi gen. nov. et sp. nov. based on the morphology of the imago, worker caste and molecular COI data.
The material examined in this study is deposited at Museu de Zoologia da Universidade de São Paulo, São Paulo, Brazil (
Some type material of old species was consulted for comparisons and remarks with R. boteroi sp. nov., to avoid generating new synonyms for described species. The abbreviations of the cited institutions are:
The terminology used to describe worker mandibles follows
In
The mandibles were examined on a microscope slide in PVA medium, after adding a cover glass and pressing them gently into position, as shown in Figure
The terms used for pilosity are comparative: bristles are stiff hairs with well-marked bases; spine-like bristles are shorter and thicker than bristles; hairs are shorter and thinner than bristles and without conspicuous bases.
Workers and imagos were examined in a petri dish filled with 80% ethanol, whereas the dissection of the enteric valve (EV) was done with two no. 20 minuten pins (BioQuip, Rancho Dominguez, CA).
The EV was detached from the paunch (P3) and all the food particles were removed by gentle manipulation. The extracted EV was inserted in a drop of PVA mounting medium (BioQuip, Rancho Dominguez, Cat. #6371A) and then gently massaged with the side of a minuten pin for a few minutes until the EV became detached from the muscles. Afterwards, the EV was transferred on to a microscope slide where, after adding another drop of the same mounting medium, the fully cleaned tubular EV was splayed open before final mounting.
The following morphometric characters were measured as defined by
Microphotographs were taken as multi-layer montages using a Leica M205C stereomicroscope for the worker head, fore tibia and mandibles; for the worker EV a Leica CTR 5500 compound microscope was used, controlled by the Leica Application Suite version 3 software.
The distribution map was created using ArcGIS desktop ver. 10.4.1 (ESRI, Redlands, CA). The list of examined material is sorted by country (uppercase), state or province, and locality. Collection data are organized as follows: latitude, longitude, collection date, altitude, collector name, collection, and collection number.
The COI barcoding region (Cytochrome c Oxidase subunit 1) was sequenced for four colonies of R. boteroi sp. nov. from Peru, Ecuador, French Guiana and Paraguay. DNA extraction and PCR were performed by the Canadian Centre for DNA Barcoding (BOLD systems), following standard high-throughput protocols (
Rustitermes boteroi sp. nov.
Enteric valve with six slightly asymmetrical cushions. Each cushion forming a central pouch made of scales smaller than those between the cushions. Each cushion composed of about 60–80 scales, wider at the base and narrower at the apex. Posterior portion of pads truncated, with 35 to 50 rectangular scales arranged from the middle to the apex of the cushion and increasing in density in this same direction.
Imago (Fig.
Measurements (mm) of imagos of Rustitermes boteroi sp. nov. from colony
Female (n = 4) | Male (n = 5) | |||
---|---|---|---|---|
Range | Mean | Range | Mean | |
Length of head | 0.78–0.92 | 0.83 | 0.65–0.78 | 0.75 |
Width of head with eyes | 1.13–1.20 | 1.18 | 1.12–1.15 | 1.12 |
Maximum diameter of compound eye | 0.27 | 0.27 | 0.27–0-28 | 0.27 |
Inter-eye distance | 0.87–0.95 | 0.93 | 0.87–0.88 | 0.87 |
Maximum diameter of ocellus | 0.12 | 0.12 | 0.11–0.12 | 0.11 |
Minimum diameter of ocellus | 0.08–0.09 | 0.09 | 0.08–0.09 | 0.09 |
Eye-ocellus distance | 0.08–0.11 | 0.1 | 0.08–0.1 | 0.09 |
Length of pronotum | 0.57–0.63 | 0.6 | 0.55–0.58 | 0.56 |
Width of pronotum | 1.00–1.08 | 1.04 | 0.97–0.98 | 0.97 |
Length of forewing with scale | 11.60–12.13 | 11.82 | 10.40–10.53 | 10.47 |
Width of fore tibia | 0.13 | 0.13 | 0.13 | 0.13 |
Length of fore tibia | 0.88–0.95 | 0.93 | 0.83–0.88 | 0.86 |
Head capsule with short, sparse bristles; coloration of head capsule dark brown; frontal marks slightly lighter than rest of head capsule, with poorly defined margins. Pronotum subhexagonal, with anterior margin straight, without central incision; lateral margins very straight and well-marked; pronotum with few sparse bristles and short hairs. Tergites and sternites with short hairs covering the plates. Fore coxa with a set of 4–5 prominent long bristles; inner face of fore tibia with two rows of 6–7 thick bristles.
Worker
(Figs
Mixed segment (MS) separated from ileum (P1) by a simple transverse junction; P1 of uniform width along entire length, forming an inverted C in ventral view. Enteric valve without armature, with six pyriform cushions of slightly different dimensions, the two largest and two smallest cushions adjacent to each other. The center of each cushion is formed into a lumen-facing pouch consisting of about 60 fringed scales. The remainder of the cushions consists of 50–75 (depending on size of cushion) larger fringed polygons. The cuticle between the cushions is composed of even larger fringed cuboidal scales. All cushions are wider at base (near P1) and narrower at apex (near P3). Tubular and short EV seating. Worker measurements highly variable among and within different colonies (Table
Measurements (mm) of 9 colonies (n = 10) of Rustitermes boteroi sp. nov. L = length, W = width.
Length of head with postclypeus | Max. width of head | Hind tibia L | Fore tibia W | Fore tibia L | Ratio fore tibia W/L | |
---|---|---|---|---|---|---|
Holotype | 0.95 | 0.95 | 0.88 | 0.18 | 0.58 | 0.30 |
PU602 | 0.79–0.89 (0.86) | 0.96–1.00 (0.99) | 0.95–1.04 (0.99) | 0.14–0.16 (0.15) | 0.74–0.79 (0.78) | 0.18–0.21 (0.20) |
AG360 | 0.8–1.05 (0.86) | 0.85–1.18 (0.92) | 0.53–0.75 (0.63) | 0.10–0.15 (0.13) | 0.43–0.53 (0.46) | 0.24–0.29 (0.28) |
BO431 | 0.82–0.96 (0.90) | 1.02–1.09 (1.04) | 0.89–0.98 (0.95) | 0.14–0.18 (0.16) | 0.72–0.77 (0.75) | 0.18–0.23 (0.21) |
EC400 | 0.92–0.95 (0.89) | 1.0–1.04 (1.01) | 0.98–1.04 (1.01) | 0.16–0.19 (0.18) | 0.77–0.82 (0.80) | 0.20–0.24 (0.23) |
|
0.80–0.84 (0.83) | 0.98–1.12 (1.04) | 0.77–0.88 (0.84) | 0.13–0.18 (0.15) | 0.63–0.72 (0.67) | 0.19–0.26 (0.22) |
FG411 | 0.80–0.85 (0.82) | 0.87–0.93 (0.89) | 0.68–0.80 (0.74) | 0.17–0.20 (0.18) | 0.55–0.58 (0.57) | 0.33–0,35 (0.33) |
PA8 | 0.82–0.89 (0.85) | 0.88–0.95 (0.91) | 0.88–0.96 (0.91) | 0.16–0.19 (0.18) | 0.68–0.75 (0.73) | 0.21–0.27 (0.24) |
TT1614 | 0.77–0.88 (0.82) | 0.86–0.91 (0.89) | 0.88–0.96 (0.90) | 0.14–0.18 (0.16) | 0.70–0.74 (0.72) | 0.19–0.24 (0.22) |
CATAC-0954 | 0.85–1.01 (0.91) | 0.93–1.02 (0.99) | 0.77–0.85 (0.82) | 0.16–0.20 (0.18) | 0.65–0.71 (0.69) | 0.20–0.24 (0.22) |
The digestive tube coiling of the new genus is similar to Hydrecotermes, but R. boteroi sp. nov. can be differentiated by the worker, which has thick bristles along the inner margin of the fore tibia, absent in Hydrecotermes. In the workers, the enteric valve and the digestive tube may be similar to Aparatermes, but the cuticle between the cushions in Aparatermes does not have cuboidal scales. In Aparatermes the insertion of P1 in P3 occurs in dorsal view with a trilobate EV setting, in Rustitermes the enteric valve seating (EVS) is not trilobate. Also, the enteric valve of Aparatermes has small spines or pointy scales, which are absent in R. boteroi sp. nov.; in addition, the EV in Aparatermes has the posterior portion of the pads without scales. The imago presents a visible molar process and fore tibia with two rows of thick bristles.
The Bayesian phylogeny using the COI marker clearly separates Rustitermes gen. nov. from the other soldierless termites (Figure
Named in honor of Michael K. Rust, retired professor of urban entomology at the University of California, Riverside (UCR), and mentor of RHS. Mike encouraged RHS to publish his first taxonomic paper (
Holotype. Worker from colony labeled as
PERU. Ucayali, Nueva Requena, -8.37007, -74.84366.
University of Florida, Fort Lauderdale Research and Education Center, Termite Collection in Davie, Florida.
Paratypes. Argentina. Corrientes, Santo Tome, (-28.57900, -56.0840), 1.JUL.1998, 93 m, J. Křeček coll. (
Unarmed enteric valve with six slightly asymmetrical cushions, each one forms a central pouch made of about sixty scales, smaller than those between the cushions.
Imago. As described for the genus.
Worker
(Figs
Enteric valve without armature, with six pyriform cushions of slightly different dimensions, each cushion consisting of 50–75 (depending on size of cushion) larger fringed polygons. The cuticle between the cushions is composed of even larger fringed cuboidal scales assembled close to P3.
See remarks for genus.
This species was collected mainly in soil, although it can also be found at the base of trees or occasionally under pieces of wood or fallen tree limbs above ground. Very common in pastures and open areas; found in young rubber crops in great abundance, less abundant in natural forests. Range: from Trinidad and Tobago to northern Argentina and the Atlantic Forest in Brazil (see discussion below); no known records for Chile and Uruguay (Figure
Named in honor of the great Colombian artist Fernando Botero.
Despite its wide distribution and abundance in disturbed sites and open areas R. boteroi sp. nov. had not been previously described, indicating the lack of taxonomic work on soldierless termites. Currently, the use of the worker caste for the taxonomic identification of termites has been shown to be increasingly necessary, regardless of the presence of imago or soldier castes (
Many other Apicotermitinae species present wide distributions in South America, such as Compositermes vindai Scheffrahn, which has been reported from Panama to Paraguay (
According to the data presented, R. boteroi sp. nov. is widely distributed in the Guiana shield, the Amazon and the Atlantic forest. An effort is needed to identify Cerrado, Caatinga and Amazonian samples (there is abundant material deposited in
Molecular phylogeny using the COI marker was useful to complement evidence of the separation of R. boteroi sp. nov. from the other Apicotermitinae genera. However, this marker alone is not enough to provide a resolved phylogeny allowing to understand the evolution of this group. The new world Apicotermitinae were determined to be monophyletic, but the relationship between most genera had very low branch support, making it impossible to provide deeper discussions.
We thank Instituto Amazónico de Investigaciones Científicas SINCHI, Gobernación del Caquetá and James A. Chase for the financial support in the Colombian Amazon. We received financial support from the São Paulo Research Foundation, Brazil (FAPESP) through grants 2014/11982-1 to J. Constantini and 2013/20068-9 to E. Cancello, and from CNPq Proc. 307681/2016-5. We thank Dr John Warner (University of Florida) for his help improving the English. Furthermore, we thank Dr Yves Roisin and Dr Thomas Bourguignon for reviewing and improving this manuscript. Special thanks to Dr Clara P. Peña-Venegas for her support in the CATAC collection. We also thank Dr Armando Sterlling and Tatiana Andrade for their help in the management of the specimens at Caquetá, Colombia.