Morphology, COI sequences and female genitalia of sand cockroaches Eupolyphaga and Pseudoeupolyphaga
NEWS - Two new species of Eupolyphaga (E. bicolor and E. nigra) and six new species of Pseudoeupolyphaga (P. flava, P. deficiens, P. magna, P. longiseta, P. latizona, and P. baimaensis) from China were described using morphological and COI sequences analyses. The researchers also reported the female external genitalia and spermathecae of both genera and the role of morphological characters.
.webp "Morphology, COI sequences and female genitalia of sand cockroaches (Eupolyphaga and Pseudoeupolyphaga)")
Eupolyphaga was once the most diverse Corydioidea in China with 22 species and 4 subspecies. However, Eupolyphaga has been revised based on a combination of morphological characteristics and phylogenetic reconstruction by moving most of the species to Pseudoeupolyphaga. Only 7 species are in Eupolyphaga, while 15 species and 4 subspecies are in Pseudoeupolyphaga.
The species identification of both genera is mainly based on some external morphology of males and the shape of the ootheca serrations. More samples are needed to evaluate the taxonomic reliability, and morphological characterization and molecular data are needed to delimit the species in the two genera of sand cockroaches.
Zong-Qing Wang and colleagues from Southwest University in Chongqing found that some Eupolyphaga specimens collected from Yunnan and Sichuan showed high morphological similarity to some known Pseudoeupolyphaga species, while the differences were subtle.
The male specimens showed similar external morphology to P. yunnanensis, although the former was significantly larger in body size. Some male specimens from Tazigou closely resembled P. simila, but had much shorter tegmina and hind wings. It is unclear whether the differences are interspecific or intraspecific variations.
The combination of morphological characters and molecular data to delimit the species of Eupolyphaga and Pseudoeupolyphaga including illustrations of genitalia, spermathecae of females and the taxonomic significance of these female characters may help to explore the diversity and basis for identifying the two genera.
Researchers using morphological data supported by molecular data found the boundary between interspecific and intraspecific genetic distances in Pseudoeupolyphaga is still unclear. The maximum intraspecific distance is 7.54%, while the minimum interspecific distance is 6.61% resulting in overlap.
Limited migration capacity of species and substantial geographic isolation may explain the larger intraspecific genetic distances. Thus, species delimitation within the genus should also consider differences in geographic distances. It is important for wider sampling, more comprehensive genetic data collection, geographic distribution or chromosome number to understand species.
The structure of female genitalia can serve as a useful character for species identification in Blattodea, despite the variation in sclerites. Previous studies on female genitalia in Corydioidea are very limited with descriptions available for only eight species in four genera.
Wang and team conducted a comparative analysis of female external genitalia and spermathecae among 8 species in Eupolyphaga and 15 species-subspecies in Pseudoeupolyphaga. They found consistent structural composition among these species with variation in the degree of sclerotization in some sclerites.
However, the roles of female external genital sclerites and spermathecae are not the same in both species. This is very suitable as a genus synapomorphy, but not effective for species delimitation. The researchers suggest that studies on female genitalia in more genera should be considered to reveal more about the taxonomic significance and evolutionary patterns.
Original research
Han W, Che Y-L, Zhang P-J, Wang Z-Q (2024). New species of Eupolyphaga Chopard, 1929 and Pseudoeupolyphaga Qiu & Che, 2024 (Blattodea, Corydioidea, Corydiinae), with notes on their female genitalia. ZooKeys 1211: 151-191, DOI:10.3897/zookeys.1211.128805
.webp "Morphology, COI sequences and female genitalia of sand cockroaches (Eupolyphaga and Pseudoeupolyphaga)")
Eupolyphaga was once the most diverse Corydioidea in China with 22 species and 4 subspecies. However, Eupolyphaga has been revised based on a combination of morphological characteristics and phylogenetic reconstruction by moving most of the species to Pseudoeupolyphaga. Only 7 species are in Eupolyphaga, while 15 species and 4 subspecies are in Pseudoeupolyphaga.
The species identification of both genera is mainly based on some external morphology of males and the shape of the ootheca serrations. More samples are needed to evaluate the taxonomic reliability, and morphological characterization and molecular data are needed to delimit the species in the two genera of sand cockroaches.
Zong-Qing Wang and colleagues from Southwest University in Chongqing found that some Eupolyphaga specimens collected from Yunnan and Sichuan showed high morphological similarity to some known Pseudoeupolyphaga species, while the differences were subtle.
The male specimens showed similar external morphology to P. yunnanensis, although the former was significantly larger in body size. Some male specimens from Tazigou closely resembled P. simila, but had much shorter tegmina and hind wings. It is unclear whether the differences are interspecific or intraspecific variations.
The combination of morphological characters and molecular data to delimit the species of Eupolyphaga and Pseudoeupolyphaga including illustrations of genitalia, spermathecae of females and the taxonomic significance of these female characters may help to explore the diversity and basis for identifying the two genera.
Researchers using morphological data supported by molecular data found the boundary between interspecific and intraspecific genetic distances in Pseudoeupolyphaga is still unclear. The maximum intraspecific distance is 7.54%, while the minimum interspecific distance is 6.61% resulting in overlap.
Limited migration capacity of species and substantial geographic isolation may explain the larger intraspecific genetic distances. Thus, species delimitation within the genus should also consider differences in geographic distances. It is important for wider sampling, more comprehensive genetic data collection, geographic distribution or chromosome number to understand species.
The structure of female genitalia can serve as a useful character for species identification in Blattodea, despite the variation in sclerites. Previous studies on female genitalia in Corydioidea are very limited with descriptions available for only eight species in four genera.
Wang and team conducted a comparative analysis of female external genitalia and spermathecae among 8 species in Eupolyphaga and 15 species-subspecies in Pseudoeupolyphaga. They found consistent structural composition among these species with variation in the degree of sclerotization in some sclerites.
However, the roles of female external genital sclerites and spermathecae are not the same in both species. This is very suitable as a genus synapomorphy, but not effective for species delimitation. The researchers suggest that studies on female genitalia in more genera should be considered to reveal more about the taxonomic significance and evolutionary patterns.
Original research
Han W, Che Y-L, Zhang P-J, Wang Z-Q (2024). New species of Eupolyphaga Chopard, 1929 and Pseudoeupolyphaga Qiu & Che, 2024 (Blattodea, Corydioidea, Corydiinae), with notes on their female genitalia. ZooKeys 1211: 151-191, DOI:10.3897/zookeys.1211.128805