Normal table of embryonic development in the four-toed salamander, Hemidactylium scutatum

Abstract

We present a complete staging table of normal development for the lungless salamander, Hemidactylium scutatum (Caudata: Plethodontidae). Terrestrial egg clutches from naturally ovipositing females were collected and maintained at 15 °C in the laboratory. Observations, photographs, and time-lapse movies of embryos were taken throughout the 45-day embryonic period. The complete normal table of development for H. scutatum is divided into 28 stages and extends previous analyses of H. scutatum embryonic development (Bishop, 1920; Humphrey, 1928). Early embryonic stage classifications through neurulation reflect criteria described for Xenopus laevis, Ambystoma maculatum and other salamanders. Later embryonic stage assignments are based on unique features of H. scutatum embryos. Additionally, we provide morphological analysis of gastrulation and neurulation, as well as details on external aspects of eye, gill, limb, pigmentation, and tail development to support future research related to phylogeny, comparative embryology, and molecular mechanisms of development.

Convergent evolutionary reduction of atrial septation in lungless salamanders

“…Hemidactylium scutatum animals were staged according to Hurney et al . (). Plethodon cinereus embryos were staged according to Kerney ().…”

“…Ambystoma mexicanum were staged according to Bordzilovskaya et al (1989) and Nye et al (2003). Hemidactylium scutatum animals were staged according to Hurney et al (2015). Plethodon cinereus embryos were staged according to Kerney (2011).…”

Comparative morphological analysis during larval development of three syntopic newt species (Urodela: Salamandridae)

“…Species differences, stage by stage, were assessed using two-way analysis of variance (ANOVA), followed by Bonferroni's post hoc test; levels of significance are indicated as *** p < 0.001; ns = not significant. Epperlein and Junginger (1982); b Glücksohn (1932); c Gallien and Bidaud (1959); d Tripepi et al (1998); e D'Amen et al 2006; f Lukanov and Tzankov (2016); g Watson and Russell (2000); h Shi and Boucaut (1995); i Hurney et al (2015); j Tarkhnishvili and Serbinova (1997).…”

“…& Bidaud 1959;Iwasawa & Kera 1980;Iwasawa & Yamashita 1991;Shi & Boucaut 1995;Tarkhnishvili & Serbinova 1997;Lukanov & Tzankov 2016). Other studies are limited to the early developmental stages, from egg fertilisation to the emergence of fore limb buds and/or hatching (Harrison 1969;Schreckenberg & Jacobson 1975;Epperlein & Junginger 1982;Marks & Collazo 1998;Tripepi et al 1998;D'Amen et al 2006;Hurney et al 2015). Lastly, post-hatching developmental staging tables are available for two species belonging to the genus Ambystoma (Watson & Russell 2000;Nye et al 2003), until metamorphosis.…”

Discovery of central Texas Eurycea eggs in the wild

“…At the same time as the two eggs were discovered in the wild, a clutch of 18 E. pterophila eggs (captive-bred F 1 generation) was produced by the captive assurance population at SMARC on 19 and 20 June 2018. Based on plethodontid embryonic development stages, the two eggs collected from the wild appeared to be at a similar stage of development as the captive-bred clutch (Hurney et al 2015). The captive-bred clutch hatched 27-37 d post-deposition.…”