Nauplius ORIGINAL ARTICLE THE JOURNAL OF THE A new “extreme” type of mantis shrimp BRAZILIAN CRUSTACEAN SOCIETY larva e-ISSN 2358-2936 Carolin Haug1,2 orcid.org/0000-0001-9208-4229 www.scielo.br/nau Philipp Wagner1 orcid.org/0000-0002-6184-1095 www.crustacea.org.br Juliana M. Bjarsch1 Florian Braig1 orcid.org/0000-0003-0640-6012 1,2 Joachim T. Haug orcid.org/0000-0001-8254-8472 1 Department of Biology, Ludwig-Maximilians-Universität München, Großhaderner Straße 2, D-82152 Planegg-Martinsried, Germany 2 GeoBio-Center, Ludwig-Maximilians-Universität München, Richard-Wagner-Straße 10, 80333 München, Germany ZOOBANK: http://zoobank.org/urn:lsid:zoobank.org:pub:135EA552-435E-45A9- 961B-E71F382216D9 ABSTRACT Mantis shrimps are prominent predatory crustaceans. Their larvae, although morphologically very differently-appearing from their adult counterparts, are already predators; yet, unlike the adults they are not benthic. Instead they are part of the plankton preying on other planktic organisms. Similar to some types of lobsters and crab-like crustaceans the planktic larvae of mantis shrimps can grow quite large, reaching into the centimeter range. Nonetheless, our knowledge on mantis shrimp larvae is still rather limited. Recently new types of giant mantis shrimp larvae with “extreme morphologies” have been reported. Here we describe another type that qualifies to be called “extreme”. Comparative measurements of certain morphological structures on selected known larvae support the exceptionality of the new specimen. It differs in several aspects from the original four types of extreme mantis shrimp larvae described by C. Haug et al. (2016). With this fifth type we expand the known morphological diversity of mantis shrimp larvae and also contribute to our still very incomplete, although growing, knowledge of this life phase. KEY WORDS Stomatopoda, Verunipeltata, giant larva, erichthus, plankton. CORRESPONDING AUTHOR Carolin Haug [email protected] INTRODUCTION SUBMITTED 11 October 2017 ACCEPTED 24 April 2018 PUBLISHED 08 October 2018 Plankton is the entirety of organisms in the water column that are unable to swim against the current (e.g., Lalli and Parsons, 1997). The metazoan DOI 10.1590/2358-2936e2018019 fraction of the plankton – zooplankton – is largely dominated by crustaceans, All content of the journal, except especially copepods (e.g., Sommer and Stibor, 2002), but more precisely, where identified, is licensed under a Creative Commons attribution-type BY. Nauplius, 26: e2018019 1 Diagramação e XML SciELO Publishing Schema: www.editoraletra1.com C. Haug et al. New “extreme” stomatopod larvae by larval forms of crustaceans. Among these forms are, and predatory nature of these larvae leaves us with a besides copepod larvae, larval stages of crabs, lobsters, strange situation. The large number of mantis shrimp shrimps, prawns, but also those of mantis shrimps larvae found in plankton samples (pers. obs.) points to (Stomatopoda, Verunipeltata). Adult mantis shrimps relatively high abundances. Hence, there appears to be are fierce predators in the benthos. Yet, their larvae a rather large fraction of the plankton that is predatory live among the plankton, but are likewise predators, on smaller plankton, and is at the same time the food preying on other planktic organisms. source for even larger predators (e.g., Brock, 1985). Although the general assumption is that being part When trying to understand food web interactions in of the plankton immediately means being small (but the oceans, the lack of knowledge about the biology see Lalli and Parsons, 1997, their fig. 1.2), crustacean of mantis shrimp larvae is quite unfortunate. larvae include exceptions to this assumption with larval Recent work on historical material of stomatopod forms reaching into the centimeter range. Among larvae provided important new findings especially these exceptions are larval forms of different lobsters widening the known morphological diversity of mantis (polychelidan lobsters, e.g., Martin, 2014; Torres et al., shrimps larvae. C. Haug and J.T. Haug (2014) reported 2014; J.T. Haug et al., 2015; Eiler and J.T. Haug, 2016; morphological adaptations of certain erichthus-type achelatan lobsters, e.g., Palero et al., 2014; J.T. Haug larvae that allow these forms to perform defensive and C. Haug, 2016), larvae of crab-like crustaceans enrolment, comparable to well known terrestrial (Martin and Ormsby, 1991; Rudolf et al., 2016), but modern arthropods such as pill bugs and pill millipedes, also the later larval stages of mantis shrimps. or the extinct marine trilobites. The latter have generally been differentiated into J.T. Haug et al. (2016) reported an unusual two types: erichthus and alima (for a more detailed intermediate stage of a small-sized stomatopod larva overview on the morphology and development of that is morphologically in the transition between the these larvae, see Ahyong et al., 2014 and C. Haug et early larval phase (antizoea) and later larval phase al., 2016). This differentiation dates back to the work (erichthus). This specimen provided important new of Giesbrecht (1910). The work of Giesbrecht (1910), reference points for understanding the composition of despite its age, is in fact still a key publication in the the raptorial appendages of modern mantis shrimps. field of mantis shrimp larvae (Ahyonget al., 2014). C. Haug et al. (2016) reported four different Since then mantis shrimp larvae have been treated morphotypes of new erichthus-type larvae with astonishingly rarely in a comparable way in the literature rather unusual or “extreme” morphologies. In all these (notable exceptions are Alikunhi, 1952, Townsley, forms the shield has very prominent modifications 1953 or Shanbhogue, 1975). It might therefore not in the one or other direction. C. Haug et al. (2016) be surprising that, although we know of about 500 suggested that most of these modifications could be species of mantis shrimps, we only know the larval understood as adaptations, allowing these forms to series of about half a dozen of these (Gohar and Al- still float in the plankton while achieving comparably Kholy, 1957; Manning and Provenzano, 1963; Pyne, large body sizes. 1972; Provenzano and Manning, 1978; Morgan and These examples show that also old plankton Provenzano, 1979; Greenwood and Williams, 1984; samples in museum collections can provide valuable Hamano and Matsuura, 1987; Morgan and Goy, 1987; contributions to our overall knowledge of biology in Diaz and Manning, 1998; see discussion in J.T. Haug general and more specifically to mantis shrimp larvae. et al., 2016) and isolated stages of a few more. Even Here we report another specimen of a mantis shrimp with modern molecular methods it is still frustratingly larva found in a museum collection. The specimen difficult to identify larvae to speciese.g. ( , Tang et al., also falls into the “extreme morphology category” 2010; but see Feller et al., 2013). but differs from the four so far known types, hence The fact that our knowledge of mantis shrimp again expanding the morphological diversity of these larvae is rather limited combined with the large size larval forms. Nauplius, 26: e2018019 2 Diagramação e XML SciELO Publishing Schema: www.editoraletra1.com C. Haug et al. New “extreme” stomatopod larvae MATERIAL AND METHODS in front of the lens were used. Cross-polarised light reduces reflections and enhances the colour contrast Material (e.g., C. Haug et al., 2011). For overcoming limitations The single known specimen central to this study of depth of field stacks of images with differing focal comes from the collection of the Museum für planes were recorded. Limitations of field of view Naturkunde Berlin. The specimen was in a plankton were overcome by documenting adjacent areas of sample together with mainly large-sized phyllosoma- the specimen with detail images (e.g., J.T. Haug et type larvae of achelatan lobsters. The sample had been al., 2008; 2011). Finally in cases of complex three- collected south of Mauritius at a depth of c. 20 m during dimensional structures specimens were documented the German South Pole Expedition (Dt. Südpolar- as stereo images, by moving the camera to some degree Expedition) on May 14, 1903. left and right e.g.( , C. Haug et al., 2011). Specimens The specimen is partly damaged (indicated by were documented from at least three sides (dorsal, crack lines). Due to the already fragile condition of the ventral, lateral) and where possible also in anterior specimen and its origin from a historical expedition, it had to be handled carefully. Hence, not all appendages and posterior view. could be positioned optimally without damaging them, and also some dirt could not be removed without Image processing further damaging the specimen and was therefore left Stacks of images were fused with the freely available in place. The specimen is deposited under collection program CombineZP. Adjacent image details were number 30023A (an older number associated with the stitched to panoramas with Adobe Photoshop CS 3 specimen is 19353). or Adobe Photoshop Elements 11. Red-cyan stereo Comparative material for measurements came from anaglyphs were assembled in Adobe Photoshop CS2. the Natural History Museum of Denmark (NHMD, Further processing such as removing dirt particles originally ZMUC-CRU for crustacean collection of the and back ground with a lasso tool, optimisation of the Zoological Museum of the University of Copenhagen). histogram, saturation and sharpness was performed in Some specimens have been presented earlier (for Adobe Photoshop CS2. details, check C. Haug and J.T. Haug, 2014, C. Haug et al., 2016 and J.T. Haug et al., 2016). Measurements Different body dimensions were measured Documentation methods which appear to represent the major determinants Specimens were kept in their original storage liquid of the general body shape, especially of the shield, (70% EtOH). They were placed in plastic containers. which corresponds to a large part of the larval body. For positioning the specimens glass blocks and large- The measured dimensions are height of the shield sized coverslips were used.