Review of morphometric measurements used in anuran species descriptions and recommendations for a standardized approach

Abstract

Standardization and repeatability is at the heart of all scientific research, yet very little literature exists to standardize morphometric measurements within vertebrate groups. This is particularly true for amphibians. Our study attempts to rectify this lack of methodological standardization for the measurement of morphological characters in anurans through an extensive literature survey of 136 species descriptions representing 45 currently recognized families of frogs. The survey revealed 42 morphological measurements represented in five percent or more of the literature reviewed. All measurements are listed by most commonly used name, acronym, and most precise definition, and we provide statistics summarizing the variation in measurement use and description from the surveyed literature. Of these 42 measurements, a subset of 16 were found in the top 75% of all surveyed descriptions and identified as a focal set of recommended measurements in an effort to standardize the morphometric measurements that describe anuran species diversity. Illustrations of these 16 measurements are provided as a visual reference for standardizing their measurement.

An acoustic and morphometric evaluation of the geographic distribution of Phyllomedusa burmeisteri (Anura: Phyllomedusidae), with comments on P. bahiana

“…Eleven traits were measured following Watters et al (2016): snout-vent length (SVL), thigh length (THL), foot length (FL), head length (HL), head width (HW), eye diameter (ED), tibia length (TL) (= shank length), tympanum diameter (TD), eye-nostril distance (END), and disc diameters of third finger (3FD) and fourth toe (4TD).…”

A new species of the toothed toad Oreolalax (Anura, Megophryidae) from Sichuan Province, China

“…Sex of individuals was determined by presence of nuptial spines on finger and chest in males in breeding condition. The terminology and methods followed Fei et al (2009) and Watters et al (2016). Measurements were taken with a dial caliper to 0.1 mm.…”

Revision of the circumtropical glasseye fish Heteropriacanthus cruentatus (Perciformes: Priacanthidae), with resurrection of two species

“…Note: this is measured along the jaw, and not parallel to the longitudinal axis of the animal), ED (horizontal eye diameter), END (eye-nostril distance, from the anterior eye to the posterior of the naris), NSD (nostril-snout tip distance, from the centre of the naris), NND (internarial distance, from the centre of each naris), TDH (horizontal tympanum diameter), TDV (vertical tympanum diameter), HAL (hand length, from the carpal-radioulnar articulation to the tip of the longest finger), LAL (lower arm length, from the carpal-radioulnar articulation to the radioulna-humeral articulation), UAL (upper arm length, from the radioulna-humeral articulation to the trunk, measured along the posterior aspect of the arm), FORL (forelimb length, given by the sum of HAL, LAL, and UAL), FOL (foot length, from the tarsal-metatarsal articulation to the tip of the longest toe), TARL (tarsal length, from the tarsal-metatarsal articulation to the tarsal-tibiofibular articulation), FOTL (foot length including tarsus, given by the sum of FOL and TARL), TIBL (tibiofibula length, from the femoral-tibiofibular articulation to the tarsal-tibiofibular articulation), TIBW (maximum tibiofibula [=shank] width), THIL (thigh length, from the vent to the femoral-tibiofibular articulation), THIW (thigh width at thickest point, measured in supine position), HIL (hindlimb length, given by the sum FOL, TARL, TIBL, and THIL), IMCL (maximum length of inner metacarpal tubercle), IMTL (maximum length of the inner metatarsal tubercle). For a figure of the application of this scheme, readers are referred to Scherz et al (2015b); for the sake of consistency, we here retain the abbreviations we have used previously instead of those proposed by Watters et al (2016). A table including all morphological measurements is provided as Appendix 1.…”