Detailed description of some mantis shrimp larvae and their implication for the character evolution within Stomatopoda

Joris Wiethase,Joachim T Haug,Carolin Haug

doi:10.1590/2358-2936e2020001

Joris Wiethase, Joachim T Haug + Show 1 more

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https://doi.org/10.1590/2358-2936e2020001

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Abstract

Abstract We present a documentation of the morphological details of two larval stages of mantis shrimps. Documentation was done using the autofluorescence capacities of the cuticle. This is the first time that morphological details of late mantis shrimp larvae are documented in great detail via photography, including all parts of the body up to the proximal elements of the appendages, and not presented as line drawings; it is the second time for mantis shrimp larvae in general. The description is presented as a standardized descriptive matrix. Documentation and description style are adjusted to facilitate comparison with fossil representatives of mantis shrimps, but also their extant counterparts, as well as specimens in the wider framework of Malacostraca and Eucrustacea. Through an exemplary comparison with fossil mantis shrimps, we provide indications about the early evolutionary history of the group. Through an out-group comparison, we identify several possible evolutionary changes of developmental timing, i.e., heterochrony, which could explain some morphological specialisations of mantis shrimps.

Highlights

Mantis shrimps (Stomatopoda) are exceptional among malacostracans in regard to their morphology
We present a documentation of the morphological details of two larval stages of mantis shrimps
We describe the morphology of larval stages of extant mantis shrimps, documented with the methodology outlined in Haug et al (2011), and compare them with fossil counterparts documented and described with the same methodology

Summary

Introduction

Mantis shrimps (Stomatopoda) are exceptional among malacostracans in regard to their morphology. Larval forms of mantis shrimps are highly specialised, and possess an aberrant set of morphological traits among crustacean larvae. This includes their large, fully functional raptorial maxilliped 2, their often large overall body size (up to 50 mm in length), the elongated head region in some species, and the hypertrophied shield (e.g., Giesbrecht, 1910). Haug et al (2011) proposed the use of auto-fluorescence in combination with digital processing for documenting the external morphology of representatives of Euarthropoda This technique proved suitable for morphological comparisons, since it effectively documents fossil (e.g., Haug et al, 2008; 2009a, b; 2010b) as well as extant specimens (e.g., Haug et al, 2011; 2012a; Rötzer and Haug, 2015; Eiler et al, 2016) in great detail. We provide a first attempt at identifying heterochronic events in mantis shrimp evolution

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