Tomocerus nan, Yu, Yang and Liu, 2018

Yu, Daoyuan, Zhang, Yating, Wang, Ziqiang, Hu, Feng & Liu, Manqiang, 2024, Unravelling the obscure homology: postembryonic development of chaetotaxic traits in a basal hexapod taxon (Collembola: Tomoceridae), Zoological Journal of the Linnean Society 202 (3), pp. 1-20 : 12

Tomocerus nan

Specimens examined. 15HN2TJ (1–5), 25.xii.2015, leg. Daoyuan Yu and Chunyan Qin.

Head: First instar ( Fig. 8A ). The pattern is identical to that of T. tropicus .

Third instar ( Fig. 8B ). Chaetal transformation similar to that of T. nabanensis at the third instar, but S0 and Pp3 become microchaetae. Secondary chaetae An1a, An1p, An3a, An3a2, An3a3, Pa5a, Pp1i, and Pp3e appear.

Adult macrochaetotaxy ( Fig. 10C ). The pattern is very similar to that of T. nabanensis , but S0 is a microchaeta.

Th. II: First instar ( Fig. 9A ). The patterns of ordinary chaetae, s-microchaetae, and pseudopores are very similar to those of T. tropicus , except that a2 is a mesochaeta. Six normal s-chaetae are present on the lateral side.

Third instar ( Fig. 9B ). Primary mesochaeta p3 becomes a macrochaeta; a6 and m6 become bothriotricha; macrochaetae a5 and ap5, and mesochaetae except for a7, m7, and p6 become microchaetae. Chaetal movement and neochaetosis of macro- and mesochaetae are very similar to those of T. tropicus . About 15 microchaetae appear in a scattered manner. The pattern of s-chaetae remains unchanged.

Adult macrochaetotaxy ( Fig. 11C ). Besides the collar and aa’ series, chaetae a3, a4, m3, and p2–4 are macrochaetae; a6 and m6 are bothriotricha.

Th. III, Abd. I, Abd. II, and Abd. III: The primary patterns ( Fig. 9A ), postembryonic changes ( Fig. 9B ), and final patterns are almost identical to those of T. tropicus , except for minor differences in chaetal positions and fewer microchaetae.

Abd. IV: First instar ( Fig. 9A ). The patterns of ordinary chaetae, bothriotricha, and pseudopores are similar to those of T. tropicus , but pm7 and ap2 are absent, and p7 is a mesochaeta. About 14–17 normal and 11–14 long s-chaetae are present. The five most posterior long s-chaetae are the longest (shorter than Abd. V), and are each associated with a mesochaeta in row p (p1–5). The other long s-chaetae are subequal in length.

Third instar ( Fig. 9B ). Primary chaeta p7 becomes a macrochaeta. Other changes are almost identical to those in T. tropicus .

Adult macrochaetotaxy. The pattern is identical to that of T. tropicus .

Abd. V: The primary pattern ( Fig. 9A ), postembryonic changes ( Fig. 9B ), and final pattern are almost identical to those of T. nabanensis , except that some mesochaetae become microchaetae in different instars.

Abd. VI: The primary chaetotaxy ( Fig. 9A ) is identical to that of T. tropicus .

Status in the later instars and adult is not observed.

S-chaetotaxy from Th. II to Abd. V

Normal s-chaetae: 6/6/5/5/5/14–17 * 11–14 (long)/6

S-microchaetae: 1/1/0/0/1/0/0.

Figures

Figure 8. Cephalic chaetotaxy of Tomocerus nan. A, First instar; (B) third instar.

Figure 9. ºergal chaetotaxy of Tomocerus nan. A, First instar; (B) third instar.

Figure 10. Cephalic chaetotaxy of the adults. A, Tomocerus tropicus; (B) Tomocerus nabanensis; (C) Tomocerus nan.

Figure 11. ºergal macrochaetotaxy of the adults. A, Tomocerus tropicus; (B) Tomocerus nabanensis; (C) Tomocerus nan. Only Ŋ. II is shown for T.nabanensis and T.nan since other segments are identical to those of T. tropicus.