Morphometric Analysis of Coptotermes spp. Soldier Caste (Blattodea: Rhinotermitidae) in Indonesia and Evidence of Coptotermes gestroi Extreme Head-Capsule Shapes.

Bramantyo Wikantyoso,Tsuyoshi Yoshimura,Shu-Ping Tseng,Setiawan Khoirul Himmi,Sulaeman Yusuf

doi:10.3390/insects12050477

Bramantyo Wikantyoso, Tsuyoshi Yoshimura + Show 3 more

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https://doi.org/10.3390/insects12050477

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Abstract

Simple SummaryThe morphological characteristics of the soldier caste in termites provide valuable taxonomic information at the species level. Head-shape variation in soldiers was often used as an indicative characteristic in some genera. While species with egg-shaped and waterdrop-shaped head capsule (HC), Coptotermes gestroi and C. curvignathus, respectively, are familiar in Indonesia, neither a measurement nor head index may avoid the subjectivity of shape interpretation. We conducted linear and geometric morphometrics analyses of soldiers’ HC of Coptotermes spp. obtained from various locations in Indonesia. Although subtle differences were observed, the posterior parts of the HC laterally expanded in a gradual manner in C. gestroi, C. sepangensis, and C. curvignathus in that order. Furthermore, three extreme head-shape variations of C. gestroi were found to exist in nature. Overall, we explicitly vocalized the complexity of utilizing HC morphometric measurement and shape for species determination in Coptotermes spp.Linear and geometric morphometrics approaches were conducted to analyze the head capsule (HC) shape of collected soldier caste specimens of Coptotermes from various locations in Indonesia. The soldiers’ morphology was observed and measured. The results of the principal component analysis of the group of all species showed two important groups of variables, i.e., the body size and setae characteristics of the pronotum and head. The multicollinearity of the morphometric variables showed the importance of body measurements as well as important alternative characteristics such as the pronotum setae (PrS) and HC setae. Four trends of HC shape were observed across the species. Interestingly, three extreme shapes were depicted by geometric morphometrics of the C. gestroi HC. The phylogenetic tree inferred from 12S and 16S mitochondrial gene fragments showed high confidence for C. gestroi populations. The lateral expansion of the posterior part of the HC across the species was in accordance with the increasing of the number of hairlike setae on the pronotum and HC. These differences among species might be associated with mandible-force-related defensive labor and sensitivity to environmental stressors.

Highlights

Termites live in a variety of ecosystems and are widely distributed in tropical as well as subtropical regions, and low- and high-altitude montane forests, and they infiltrate urbanized zones [1,2]
Our current study suggested that PS shape (Figure 7) in the ventral view is an additional important characteristic for discriminating C. elisae and C. curvignathus from C. gestroi, while PS shape in the lateral view (Figure 8) can be used to discriminate C. elisae, C. curvignathus, and C. gestroi from C. sepangensis and C. kalshoveni
Head width (HW), pronotum setae (PrS), and postmentum (PS) characteristics appeared to be important in the discrimination process

Summary

Introduction

Termites live in a variety of ecosystems and are widely distributed in tropical as well as subtropical regions, and low- and high-altitude montane forests, and they infiltrate urbanized zones [1,2]. C. gestroi behavior was observed attacking harvested and readily packed mangoes (Mangifera indica L.), which is unusual behavior for termites [15]. Despite their taxonomical complexity, all the aforementioned species are known to be well-distributed as termite pests in the realm of Malesiana. By collecting a considerable amount of HC morphometric data, they argued that both C. havilandi and C. javanicus were synonyms of C. gestroi They argued that C. travians, identified in several published studies [23,24,25,26,27], was a misidentification of C. gestroi due to the use of continuous variations. In Odontotermes, Reticulitermes, and Heterotermes, other characteristics’ variations such as setae positions and numbers were found to be important and different [28,29,30,31,32]

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