Morphology of stomatopod larvae from National Parks : Sistema Arrecifal Veracruzano and Arrecife Puerto Morelos , Mexico

Th e present study provides information on the morphology of stomatopod larvae found in two diff erent reef systems which are also considered national parks: the Sistema Arrecifal Veracruzano (SAVNP) and Arrecife Puerto Morelos (APMNP). Zooplankton samples were collected at 26 stations of the SAVNP and four stations of the APMNP. Stomatopod larvae were identifi ed and classifi ed by their larval stage. We found representatives of three stomatopod superfamilies: the superfamily Gonodactyloidea Giesbrecht, 1910 was represented by Neogonodactylus oerstedii (Hansen, 1895), Neogonodactylus wennerae Manning and Heard, 1997, and Pseudosquillidae genus and species indeterminate; the superfamily Lysiosquilloidea Giesbrecht, 1910 was represented by Lysiosquilloidea genus and species indeterminate, Lysiosquilla sp., Lysiosquilla scabricauda (Lamarck, 1818) and Nannosquilla adkisoni Camp and Manning, 1982; the superfamily Squilloidea was represented by larvae of Alima neptuni (Linnaeus, 1768), Squilla spp., and Squilla empusa Say, 1818. We were able to identify and describe four stages of larval development for www.scielo.br/nau www.crustacea.org.br orIgInal artIcle Nauplius, 26: e2018005 CORRESPONDING AUTHOR Sergio Cházaro-Olvera chazaro@campus.iztacala.unam.mx SUBMITTED 21 March 2017 ACCEPTED 7 August 2017 PUBLISHED 15 March 2018 DOI 10.1590/2358-2936e2018005 orcid.org/0000-0002-0667-0043 All content of the journal, except where identi ed, is licensed under a Creative Commons attribution-type BY. orcid.org/0000-0003-0531-5557 Cházaro-Olvera et al. 2 Larval morphology of mantis shrimps Diagramação e XML SciELO Publishing Schema: www.editoraletra1.com Nauplius, 26: e2018005 representatives of these superfamilies. This is the first study describing several stages of larval development of different species of the stomatopods from the Gulf of Mexico and Caribbean Sea.


IntroductIon
The order Stomatopoda Latreille, 1817 consists of 481 species distributed in the tropical, subtropical and temperate regions of the world (Reaka et al., 2009).During their development, stomatopods pass through different larval stages and could form part of both zooplankton and benthos (Ahyong et al., 2014).
Four morphological types of stomatopod larvae are known: antizoea and pseudozoea are early larval stages, while erichthus and alima are late larval stages (Ahyong, 2004;Schram et al., 2013).These forms do not necessarily have to be sequential.To date, three alternative sequences of larval development have been identified: antizoea/erichtus, pseudozoea/erichtus, and pseudozoea/alima (Ahyong et al., 2014).The antizoea, the type in which the lysiosquilloids (and probably erythrosquilloids) hatch, is characterized by the presence of sessile eyes, antennules with a flagellum, five pairs of biramous thoracic appendages called maxillipeds (which are the most important differential characters among stomatopods), and the absence of appendages on the pleon.The carapace has a fixed spinous rostrum and covers most of the pleon except the last two or three pleomeres (Ahyong et al., 2014).Squilloids, gonodactyloids, parasquilloids and some eurysquilloids hatch as pseudozoea.This larva is characterized by having pedunculated composite eyes, biflagellate antennules, two pairs of uniramous thoracic appendages (maxillipeds 1 and 2), and four (squilloids) or five pairs of biramous swimmers (pleopods).Both, antizoea and pseudozoea of gonodactyloids, parasquilloids and eurysquilloids develop into an erichthus larva type.This larva presents the second maxilliped as a rapacious claw, with some teeth in the occlusal margin of the dactyl; maxillipeds 3-5, pereopods and uropods are absent and present one or two intermediate denticles on the telson.Finally, squilloid pseudozoea develops into alima type larva, being unique for the squilloids.This larva differs from the erichthus by presenting a ventral spine on the antennular segment and four or more intermediate denticles on the telson (Ahyong et al., 2014).
Of the approximately 500 species of stomatopods described so far, no more than 10% of the larval stages can be identified worldwide (Diaz, 1998;Haug et al., 2016).Moreover, there are only a few studies where the complete larval development of stomatopod larvae has been described (Manning and Provenzano, 1963;Pyne, 1972;Provenzano and Manning, 1978;Greenwood and Williams, 1984;Hamano and Matsuura, 1987;Morgan and Goy, 1987).Likewise, partial larval series are known for a limited number of species (Gurney, 1946;Alikunhi, 1967;Michel, 1968;1970;Michel and Manning, 1972;Shanbhogue, 1975;Rodrigues and Manning, 1992;Ahyong, 2002;Veena and Kaladharan, 2010;Feller, 2013;Antonio-Bueno, 2015).This lack of information is due in part to the complexity of the larval development of stomatopods, where the initial stages are propelagic and the late stages are planktic (pelagic) (Hamano and Matsuura, 1987).First, the female mantis shrimp will provide maternal care by using her maxillipeds to clean the eggs and circulate water around them; after hatching of the larvae, the female will continue protecting the newly hatched larvae and physiological adaptations make the early larval stages stay within the cave with the parental female, thus the first stages may be overlooked (Wortham-Neal, 2002).Maintaining an ovigerous female in captivity until hatching is by itself a difficult task, add to that the behavior of the parental female who will hide in a cave with the eggs first and later with the larvae and the task becomes almost impossible (Pyne, 1972).Besides changes on physiology, ethology and ecology of the larvae described above, the time of development is very large, from 35 days to nine months, depending on the species.No wonder why the most common way of describing stomatopod larvae is by collecting planktic stages, with the unintended consequences of describing only the later stages of development (Ahyong et al., 2014).

Larval morphology of mantis shrimps
Nauplius, 26: e2018005 Thus, the objective of this study was to provide additional information on the morphology of the planktonic larvae, at different stages of development, of some of the stomatopod species found in the southwestern Gulf of Mexico and the Mexican Caribbean, specifically on the Sistema Arrecifal Veracruzano and Arrecife Puerto Morelos.

MaterIal and Methods
The Sistema Arrecifal Veracruzano (SAVNP) is a coral reef system located in the northwest sector of the Bay of Campeche, in the polygon delimited by 19°00'00" -19°16'00"N and 95°45'00" -96°12"00"W.It is formed by 23 coral reefs distributed in a northern group and a southern group, separated by the mouth of the Jamapa River (Granados et al., 2007).The Arrecife Puerto Morelos National Park (APMNP) is part of the Mesoamerican Reef System which is in Puerto Morelos, Quintana Roo (20°54'16"N 86°49'39" W).The reef lagoon is connected to the open sea by two entrances.
The bottom of the lagoon is covered with calcareous sand and stabilized by seaweed grasslands; patches of corals have colonized some areas becoming coral reef communities (Humann, 2002;Álvarez-Cadena et al., 2007) (Fig. 1).
Field work on SAVNP: zooplankton samples were collected at 26 stations of the SAVNP.Trawls were made in the surface layer of the water column using conical plankton nets with a mesh light of 330 μm during five minutes, at a speed of three knots.The material was fixed in a 70% solution of ethanol and put in plastic containers previously labeled, and transferred to the Ecology Laboratory of the Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México (UNAM).
Field work in APMNP: two types of sampling were carried out: light traps were placed on three piers of the docking area of the Institute of Marine Sciences and Limnology during three nights, covering a 12 h cycle; these cycles were initiated at 18:00 h and stopped

Larval morphology of mantis shrimps
Nauplius, 26: e2018005 at 6:00 h of the next day on June 6, 7 and 8 on phase new moon.All traps had white light of 38 lumens.These traps were constructed with plastic boxes 0.4 m long, 0.25 m wide and 0.30 m high; a 40 mm diameter inlet holes were made in the upper part of each side of the box.
The contents were collected manually and concentrated in 500 ml plastic bottles at the end of the sampling period.The second sampling point was at the site called Rodman, where the sample was obtained in a coral stand at a depth of 20 m with SCUBA selfcontained diving equipment.The substrate was placed in plastic bags for further review.All samples were preserved with 70% alcohol.

Larval morphology of mantis shrimps
Nauplius, 26: e2018005 results We collected 1759 stomatopod larvae belonging to three superfamilies, six families, seven genera and 10 species.The superfamily Gonodactyloidea Giesbrecht, 1910 was represented by Neogonodactylus oerstedii, N. wennerae and Pseudosquillidae genus and species indeterminate.The superfamily Lysiosquilloidea was represented by Lysiosquilloidea genus and species indeterminate, Lysiosquilla sp., L. scabricauda, and Nannosquilla adkisoni.Representatives of the superfamily Squilloidea Latreille, 1802 were also present as larvae of Alima neptuni (Linnaeus, 1768), Squilla spp., and S. empusa.Overall, we found larvae of nine stomatopod species at the SAVNP and of four at the APMNP.All morphological measurements are shown on Tab. 1 and Tab. 2.

Location. SAVNP.
Stage VI: Erichthus (CNCR32470) (Fig. 3D) Description.Carapace longer than width, extending to first pleonite, bearing well-developed supraorbital spines.Rostrum not exceeding flagellum of A1.Posterolateral spines reaching third pleonite, with small proximal spine.Propodus of second maxilliped armed with at least 10-13 small denticles, long sharp proximal spine, dactyl with basal bulge.Telson straight, bearing three pairs of fixed lateral spines and pair of strongly elongated lateral spines; bearing 22 denticles on each side of midline.Uropods fully developed.

Genus and species indeterminate
Stage (Indeterminate): Erichthus (CNCR32473) (Fig. 3G) Description.Carapace short, extending to fourth pleonite, slightly wider at base, bearing fine pairs of marginal spines, presenting pair of anterolateral spines.Rostrum relatively long reaching base of flagellum of A1, lacking ventral spines.Posterolateral spines reaching last pereonite, bearing well-developed proximal spine.Second maxilliped well developed, broadened propodus with 15-17 denticles and mobile dactyl.Telson straight, bearing three pairs of fixed lateral spines and pair of lateral spines; bearing seven denticles on either side of midline. Habitat.Pelagic.

Genus and species indeterminate
Stage (Indeterminate): Antizoea (CNCR32474) (Fig. 3H) Description.Carapace globular, not widening at base of posterolateral spines, slightly rectangular.Rostral spine as long as half length of carapace; lacking ventral spines.Posterolateral spines strong and slightly curved, middle spine present; pereopods well-developed.Second maxilliped not well differentiated.Telson straight bearing three spines on margin and welldeveloped lateral spine on each side, with 12 spines on each side of midline.

Larval morphology of mantis shrimps
Nauplius, 26: e2018005 middle spine present.Pereopods well developed.Second maxilliped not well differentiated.Telson straight bearing three lateral spines; posterior margin bearing well-developed posterolateral spine on each side, with four short submedian spines, followed by long and two short spines on each side of midline; cleft present at midline.

Nannosquilla adkisoni Camp and Manning, 1982
Stage (Indeterminate): Erichthus (CNCR32477) (Fig. 3K) Description.Carapace longer than wide, with pair of small anterolateral spines.Rostrum half length of carapace, without ventral spines.Extremely long posterolateral spines reach beyond telson.Second maxilliped bearing 25-28 denticles; dactyl bearing six teeth.Spines of basal prolongation of uropod of same size.Telson straight with three movable spines on posterior margin, large lateral spines and eight denticles on each side of midline, with 2-9 spines between each pair of denticles.Uropods well developed, with spines on exopod.

Alima neptuni (Linnaeus, 1768)
Stage IV: Alima (CNCR32478) (Fig. 4A) Description.Carapace three times longer than width, extending to middle of fourth pereonite, with pair of small anterolateral spines, bearing pair of posterolateral spines reaching base of sixth pereonite, presenting small spinule and small spine proximally; margin of carapace convex.Rostrum small, reaching half of A1.Second maxilliped with proximal spine; propodus eight times as long as wide, distal portion of upper margin pectinate with 28-29 denticles; dactylus bearing three teeth.Telson convex, twice as long as wide, bearing eight intermediate and 12 submedian denticles on either side of midline. Habitat.Pelagic.

Location. SAVNP.
Stage IX: Alima (CNCR32479) (Fig. 4B) Description.Carapace three times longer than wide, extending to sixth pereonite; bearing strong anterolateral spines that reach eighth pereonite; posterolateral spines much less pronounced than anterolateral ones; bearing small dorsal spine; margin of carapace strongly convex, armed with 12 spines.Antennules, maxillipeds and pleopods well developed.Second maxilliped with spine on basal portion, propodus eight times as long as wide, dorsodistal margin pectinate with 30-32 denticles; dactylus bearing six teeth.Telson convex, twice as long as wide, bearing intermediate, submedian and lateral spines, all with movable apexes, bearing

Squilla sp. 1
Stage IX: Alima (CNCR32480) (Fig. 4C) Description.Carapace three times longer than width, reaching sixth pereonite, concave margin with nine spines on each side, presenting pair of anterolateral spines, pair of short posterolateral spines extending to fifth pereonite, with small dorsal spine.Antennules, maxillipeds and pleopods well developed.Second maxilliped with spine on basal portion, propodus eight times as long as wide, distal portion of upper margin pectinate with 28-29 denticles; dactyl smooth.Telson concave, ornamented with defined medium carina, presents 10 intermediate denticles and 18 submedian spines on each side of midline.

Squilla sp. 2
Stage II: Alima (CNCR32481) (Fig. 4D) Description.Carapace triangular, slightly convex, with three pairs of spines on posterolateral margin, presenting pair of anterolateral spines, pair of extremely long posterolateral spines reaching middle of telson, bearing proximal spine at base.Rostrum long, twice as long as A1, lacking ventral spines.Second maxilliped elongate; propodus with strong terminal tooth followed by seven denticles on inner margin; dactylus with distal portion of cutting edge as small saw.Telson concave, slightly longer than wide, with six intermediate denticles and nine submedian denticles on either side of midline. Habitat.Pelagic.

Squilla empusa Say, 1818
Stage I: Alima (CNCR32482) (Fig. 4E) Description.Carapace slightly longer than broad, moderately globose; convex margin armed with four ventral spines on each side; with pair of anterolateral spines and dorsal medial spine.Rostrum extending slightly beyond flagellum of A1; lacking ventral spines.Posterolateral spines armed with ventral spine extending to fourth pleonite.Second maxilliped large; propodus with strong terminal tooth followed by 18 to 19 denticles on inner margin; dactylus with distal portion of cutting edge as small saw.Telson concave, bearing four pairs of intermediate and 15 submedian denticles covered with spinules. Habitat.Pelagic.

Location. SAVNP.
Stage II: Alima (CNCR32483) (Fig. 4F) Description.Carapace longer than wide and moderately globose; convex margin armed with four ventral spines on each side; bearing pair of anterolateral spines and dorsal medial spine.Rostrum reaching beyond flagellum of A1; bearing four ventral spinules.Posterolateral spines armed ventrally with spine extending to base of telson.Second maxilliped elongate; propodus bearing proximal tooth followed by another large tooth and 19-20 denticles along inner margin; dactylus with distal portion of cutting edge as small saw.Telson concave, bearing four pairs of intermediate and 15 submedian denticles covered with spinules. Habitat.Pelagic.

Larval morphology of mantis shrimps
Nauplius, 26: e2018005 Stage III: Alima (CNCR32484) (Fig. 4G) Description.Carapace longer than wide, trapezoid, convex margin armed with two anterior and three posterior ventral spinules on each side, with pair of anterolateral spines and one dorsal medial spine.Rostrum long, twice as long as A1; bearing more than four ventral spines.Posterolateral spines armed ventrally with spine extending to end of telson.Second maxilliped large; propodus bearing 24-26 denticles, basis bearing proximal spine well developed; dactylus with distal portion of cutting edge as small saw.Telson concave with 8-10 pairs of intermediate denticles and 15-27 submedian denticles covered with spinules.

Location. APMNP. dIscussIon
The most recent account of species of adult stomatopods in the Gulf of Mexico and Caribbean Sea lists 45 species contained in four superfamilies and 11 families (Reaka et al. 2009;García-Calzada, 2013).Only four complete larval development of the 45 species found in the area have been described in laboratory (Manning and Provenzano, 1963;Provenzano and Manning, 1978;Morgan and Provenzano, 1979;Morgan and Goy, 1987;Rodrigues and Manning, 1992).We found larval stages of nine of those species at the SAVNP and four at the APMNP.Although the number represents only a fifth of the total number of species reported for this area, it is remarkable since it is only the first study on the morphology of stomatopod larvae for the south of the Gulf of Mexico and the Caribbean Sea.
We were able to identify larvae of two of the seven species of Neogonodactylus Manning, 1995 present in the study area, N. wennerae and N. oerstedii, although we only found two and four stages of N. wennerae and N. oerstedii, respectively.The complete larval development has been described for both species from specimens cultured in laboratory conditions (Manning and Provenzano, 1963;Provenzano and Manning, 1978;Morgan and Goy, 1987).These two species present three propelagic and four pelagic stages (Morgan and Goy, 1987).From those we found a pseudozoea and five erichthus.To differentiate these two species in stage IV erichthus we used the number of aesthetascs on first maxilliped as a diacritic character; N. wennerae presents six aesthetascs, while N. oerstedii presents eight.These two species are a rare example of the complexity of the larval development of stomatopods.During their long larval development, which takes five weeks in laboratory conditions (Provenzano and Manning, 1978), their first three larval stages are propelagic and the other four are planktonic (Dingle 1969;Provenzano and Manning 1978).Distribution in the water column of these larval stages is not a mere accident; the propelagic larvae do not hunt, they are lecitotrophic.
In addition, they present two behaviors that make them unique among crustaceans, they are thigmokinetic and present negative phototaxis.Thus, they feed on embryonic material, hide from light and grab any solid that comes in contact with them (Dingle, 1969).The result is that they keep hiding under the protection of the mother (Dingle, 1969).Thus, our finding of one of these propelagic stages is remarkable since most of the time only the pelagic stages will be found.These pelagic stages change dramatically the morphology and habits of the larvae.For instance, they will become planktotrophic (will actively hunt), will be attracted
On the other hand, we were able to identify the larvae of A. neptuni because of the size and morphological characters of both the carapace and telson.Larva of this species was described based on plankton samples (Manning, 1962, as A. hyalina Leach, 1817).There are two species of Alima distributed in the West Atlantic, A. neptuni and Alima hildebrandi (Schmitt, 1940).The former has been found in the Gulf of Mexico and Florida Keys, besides some other localities in the West Atlantic, while the latter is considered to be of amphi-Atlantic distribution, although never found within the Gulf of Mexico (Reaka et al., 2009).In this study A. neptuni was represented by two larval stages.
The superfamily Lysiosquilloidea was represented by larvae of an unidentified genus and species of Lysiosquilloidea and an unidentified species of Lysiosquilla; both were found in the stage of antizoea (first phase of the larval development).Thus, the morphological characters used for identification were referred to Townsley (1953), who reported birramous thoracic appendages, where propodus of the four thoracic appendages are rounded, broader than long, and more than twice the fifth appendage.The telson is straight.In addition, we also identified one of the last larval stages of L. scabricauda.The larva can be traced back to the adult based on characters of the telson, the shape of the corneas and the edge of pereonites as reported by García-Calzada (2013).The most current literature recognizes two species of Lysiosquilla within the Gulf of Mexico and adjacent waters (Reaka et al., 2009).These are Lysiosquilla campechiensis Manning, 1962 and L. scabricauda.We were able to recognize one larvae of L. scabricauda.However, we were unable to identify a second larval specimen of Lysiosquilla sp.Since there are two other species of this genus distributed in the study area, it may well be that the second larva belongs to one of those species, or even to Lysiosquillina glabriuscula (Lamarck, 1818) that is also distributed within the Gulf of Mexico.However, Giesbrecht (1910) has described nine pelagic stages for Lysiosquilla sp. but the adult form was not described.For the time being we cannot place our larva in any of those species of Lysiosquilla or Lysiosquillina glabriuscula.We wait either for a complete description of the larval development based on larvae reared on laboratory conditions or for a DNA analysis allowing the identification of our specimen.
The characters of Pseudosquillidae fit the description of other members of this genus (Brooks, 1886;Townsley, 1953).The telson is nearly rectangular, with eight denticles between submedian denticles and the eyes are not borne on long stalks as in alima of Squilla.The second maxilliped has the propodus finely pectinated along the upper margin and a dactylus with a single spine; the carapace is trispinous anteriorly, posteriorly bearing two long spines reaching the second pleonite.Considering the adult distribution and the observed characters, this individual may correspond to a specimen of Pseudosquilla ciliata (Fabricius, 1787) in its early larval stages.However, we could not place it based only on morphological characters and it remains as Pseudosquillidae.It is noteworthy that Townsley (1953) has described seven larval stages for this species.Morgan and Provenzano (1979) reported that S. empusa undergoes nine pelagic stages before attaining the postlarval stage.Likewise, the authors mentioned that larvae of S. empusa may be identified by the spinules of the carapace and the intermediate denticles of the telson; stages I and II possess four spinules on the lateral margin of the carapace and four intermediate denticles; the third to ninth stages are armed with six spinules on the lateral margin of the carapace; there are two anterior and three posterior spinules all ventrally directed, and one median spinule laterally directed; the telson of the stages third to ninth have 8 to 10 intermediate denticles.The species Squilla sp. 2 shows all the characters of the larvae alima like the ornamentation on the telson, characteristic of the genus.However, it does not correspond with the description of S. empusa, due to the shape of the carapace.In Squilla sp. 2 the carapace is triangular, with three pairs of spines on lateral margin; in contrast, the carapace of S. empusa is longer than wide and moderately globose and the lateral margin is armed with four ventral spines on each side.Likewise, the larvae alima of Squilla sp. 1 in stage IX is larger and wider than S. empusa in the same stage.There are also differences in the ornamentation of the second maxilliped and telson.Thus, we are certain that these two larval stages, Squilla sp. 1 and Squilla sp. 2, fit the general morphology of Squilla.However, at this time we are unable to identify to species level these two specimens that could belong to any of the three species distributed in the area of study, Squilla chydaea Manning 1962, Squilla edentata edentata (Lunz, 1937) or Squilla rugosa Bigelow, 1893.

Larval morphology of mantis shrimps
Nauplius, 26: e2018005 This study shows how it is possible to identify the larvae collected in zooplankton samples, even with only a few studies available describing a small number of stomatopod species.At the same time, it also shows that our knowledge about stomatopod larvae is scarce.It should be noted that if larval descriptions are scarce, the knowledge about their ecology is almost nonexistent.Some of the reasons for this lack of information are due to the complexity of the life history of these critters, as discussed above.Most of the observed characters agree with the original descriptions, which allowed the identification at specific level, although some differences were found.In others studies, it has been reported that there is an important variability in the intraspecific morphological characters of larvae reared under controlled conditions.Likewise, there is an important morphological variation of a species found in different regions (Criales and Anger, 1986;Pechenik, 1999;González-Gordillo and Rodríguez, 2000).The variety in the morphology of these larvae clearly shows extreme adaptations that we still do not fully understand.

acKnowledgeMents
The authors are grateful for the support of the funds granted for this research to the program PAPIIT grant number: IN220715 of the Universidad Nacional Autónoma de México (UNAM).Also to the authorities of SEMARNAT, CONANP and CONAPESCA-DGOPA (SAGARPA) for the permits granted (PPF/ DGOPA-051/15).RR has a postdoctoral fellowship by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brazil.We are also grateful to the anonymous reviewers who kindly improved the manuscript with their helpful comments.