A second new species of ice crawlers from China (Insecta: Grylloblattodea), with thorax evolution and the prediction of potential distribution

Abstract

Modern grylloblattids are one of the least diverse of the modern insect orders. The thorax changes in morphology might be associated with the changes of the function of the forelegs, wing loss, changes in behavior and adaptation to habitat. As temperature is the main barrier for migration of modern grylloblattids, the range of each species is extremely limited. The potential distribution areas of grylloblattids remain unclear. A second new species of ice crawlers (Insecta: Grylloblattodea), Grylloblattella cheni Bai, Wang et Yang sp. nov., is described from China. The distribution map and key to species of Grylloblattella are given. A comparison of the thorax of extant and extinct Grylloblattodea is presented, with an emphasis on the pronotum using geometric morphometric analysis, which may reflect thorax adaptation and the evolution of Grylloblattodea. Potential global distribution of grylloblattids is inferred. Highly diversified pronota of extinct Grylloblattodea may reflect diverse habitats and niches. The relatively homogeneous pronota of modern grylloblattids might be explained by two hypotheses: synapomorphy or convergent evolution. Most fossils of Grylloblattodea contain an obviously longer meso- and metathorax than prothorax. The length of the meso- and metathorax of modern grylloblattids is normally shorter than the prothorax. This may be associated with the wing loss, which is accompanied by muscle reduction and changes to the thoracic skeleton system. Threats to grylloblattids and several conservation comments are also provided.

Figure 1. Grylloblattella cheni Bai, Wang et Yang sp. nov.

(A) Female. (B) Habitat. (C) Type localities of all known three species of Grylloblattella.

Figure 2. Grylloblattella cheni Bai, Wang et Yang sp. nov., female.

(A) Habitus, lateral view. (B) Head, dorsal view. (C) Pronotum, dorsal view. (D) Cervical sclerites and eusterna of prothorax, ventral view. (E) Ovipositor, lateral view. (F) Ovipositor, dorsal view. (G) Basal antennomeres, left. (H) Lacinia with two preapical teeth, left. (I) Cercus, left.

Figure 3. Pronotum shape variation test and shape differences of 13 grylloblattids genera.

(A) Shape variation test tps-SMALL 1.2. (B) Ordination of the 13 grylloblattids genera means along the three canonical varieties axes based on the Procrustes distance matrix. (1) Blattogryllulus; (2) Parasheimia; (3) Plesioblattogryllus; (4) Sojanorapbidia; (5) Sylvamicropteron; (6) Sylvonympha; (7) Tataronympha; (8) Tillyardembia; (9) Galloisiana; (10) Grylloblatta; (11) Grylloblattella; (12) Grylloblattina; (13) Namkungia. Green circle includes the extant 5 grylloblattids genera.

Figure 4. Pronotum shape differences of 13 grylloblattids genera.

(A) Relative warps computed from the data set, plotted against one another to indicate positions of the relationships among genera relative to one another and to the reference configuration (situated at the origin). The shape changes of different families implied by variation along the first two relative warp axes. Shape changes are shown as deformations of the GLS reference, using thin-plate splines. (B) Phenetic tree (UPGMA), the trees compiled using NTSYS-pc based on Procrustes distances among the genera.

Figure 5. The comparison of the prediction map of grylloblattids and the map of Population Density of the world.

(A) Prediction of potential distribution areas of grylloblattids; black dots  =  selected known localities, green areas  =  potential distribution areas, red circles  =  the most potential areas, blue circle  =  the least potential areas. (B) Population Density of the world in 2000 (after CIESIN and CIAT 2005). (C) Population Density of the world in 2015 (after CIESIN, FAO and CIAT 2005).

Figure 6. Prediction map of grylloblattids based on the 19 coordinates of terrestrial ice crawlers.

(A) Prediction of potential distribution areas of grylloblattids. (B) Areas in the US with the most potential. (C) Areas in Asia with the most potential areas. Black dots  =  selected known localities, purple areas (in A)  =  potential distribution areas, green areas (in B or C)  =  potential distribution areas, red circles (in A)  =  areas with the most potential.

Figure 7. Pronotum shape of 13 grylloblattids for the geometric morphometric analysis.

(A) Blattogryllulus mongolicus Storozhenko, 1988 (Fossil). (B) Parasheimia truncata Aristov, 2004 (Fossil). (C) Plesioblattogryllus magnificus Huang, 2008 (Fossil). (D) Sojanorapbidia martynovae Storozhenko et Novokshonov, 1994 (Fossil). (E) Sylvamicropteron harpax Aristov, 2004 (Fossil). (F) Sylvonympha tshekardensis Novokshonov et Pan'kov, 1999 (Fossil). (G) Tataronympha kamensis Aristov, Novokshonov et Pan'kov, 2006 (Fossil). (H) Tillyardembia antennaeplana Zalessky, 1938 (Fossil). (I) Galloisiana chujoi Gurney, 1961. (J) G. kiyosawai Asahina, 1959. (K) G. kosuensis Namkung, 1974. (L) G. nipponensis (Caudell et King, 1924). (M) G. odaesanensis Kim et Lee, 2007. (N) G. olgae Vrsansky et Storozhenko, 2001. (O) G. sinensis Wang, 1987. (P) G. ussuriensis Storozhenko, 1988. (Q) G. yezoensis Asahina, 1961. (R) G. yuasai Asahina, 1959. (S) Grylloblatta barberi Caudell, 1924. (T) G. campodeiformis Walker, 1914. (U) G. chandleri Kamp, 1963. (V) G. gurneyi Kamp, 1963. (W) G. sculleni Gurney 1937. (X) Grylloblattella cheni Bai, Wang et Yang sp. nov. (Y) G. pravdini (Storozhenko et Oliger, 1984). (Z) G. sayanensis Storozhenko, 1996. (AA) Grylloblattina djakonovi Bey-Bienko, 1951. (AB) Namkungia biryongensis (Namkung, 1974).