Lysiosquilloidea, Erichthus

Steck, Mireille, Winnicki, Elizabeth, Kobayashi, Donald R., Whitney, Jonathan L., Ahyong, Shane T. & Porter, Megan L., 2022, Hawaiian larval stomatopods: molecular and morphological diversity, Zootaxa 5214 (2), pp. 235-260 : 244-246

Lysiosquilloidea

Lysiosquilloid larvae could be separated from other erichthus-type larvae by the presence of sub-quadrate shaped maxillipeds, a distinguishing trait in adult lysiosquilloid stomatopods as well.Another obvious trait of the lysiosquilloid larvae was the deeper, and bulkier carapace than most other groups. In most subtypes (with the exception of the Rockets), the body of the animal could curl to fit snugly into the carapace, forming a defensive ball ( Figure 5E ). Only three lysiosquilloid species have been previously documented in the Hawaiian Islands: Lysiosquilla maculata , Acanthosquilla multifasciata (Wood-Mason, 1895) , and Heterosquilloides insignis (Kemp, 1911) ( Ahyong 2002a) . Based on barcoding, we identified six lysiosquilloid OTUs from Hawaiian waters, indicating a higher diversity than previously estimated. It is unlikely the higher diversity is a result of new colonization events, and more likely an absence of adult documentation due to the cryptic and burrowing nature of Lysiosquilloidea species ( Caldwell 1988). Because of the difficulty in collecting adult Lysiosquilloidea , there is little barcoding data available for species in this superfamily. Only two OTUs were identified to species: L. maculata and Pullosquilla n. sp. ( Fig. 3 ).

The six molecular OTUs were sequenced from five distinct erichthus-type subtypes and two individual antizoea (not morphologically characterized here). Morphological differences observed among the lysiosquilloid larvae were primarily related to the carapace shape and length in comparison to the abdominal somites, and telson features ( Table 4 ). Adults of this superfamily occur in intertidal to upper slope habitats where they burrow in sand and sandy-mud ( Ahyong 2001). Adults may be found in simple sand and mud flats as well as in sandy habitats associated with reefs. Larvae were found similarly across a range of pelagic habitats, occurring both in nearshore shallow plankton tows (0–10 m), and in our deepest reef pelagic trawls (650–973 m). While the lowest number of individual lysiosquilloid larvae were found, the number of morphotypes were the second highest among the superfamilies (second only to the gonodactyloids).

Figures

FIGURE 3. Maximum likelihood phylogeny of adult and larvalstomatopod COI barcode sequences.Larval OTUs and associated morphotype-subtype designations include sequences from fourAlima-type larvae OTUs (SquATA, B, C—shield), 18 Erichthustype OTUs (LyET A—flying saucer, LyET B—spiny balloon; ProET A—Gnome Hat; GonET A—Blow Dart; LysET A, B— Tank; NanET A, B—rocket; PseET A, B, C—Torpedo; OdoET A, B, C—Lance; UnET A, B—Brawny), and one Az (antizoea stage) OTU. Bold names indicate adult and larval specimens sequenced in this study; regular font used for publicly available sequences for species which were not identified from Hawaiian larvae. The number of larvae sequenced are in parentheses before OTU morphotype-subtype identities. Relevant family names are given for highlighted clades, superfamily names or abbreviations in the outer right column (Eu: Eurysquilloidea, Pa: Parasquilloidea, Go: Gonodactyloidea, Ly: Lysiosquilloidea), unknown superfamily represented by gray bars. Silhouettes of larval sub-types within the phylogeny are in black font (two rocket sub-type silhouettes are shown), grayed sub-types are shown in the inset. Note that brawny subtype-silhouette is the only one to include raptorial appendage depiction.

FIGURE 5. Lysiosquilloideaerichthus-type larval subtype andmorphotype morphology.Tank types: LysETA—Lysiosquillidae ventral (A) and dorsal (B) views; LysET B—Lysiosquillidae ventral (C), dorsal (D), and lateral defensive posture (E) views. Rocket types: NanET A—Pullosquilla n. sp dorsal view (F); NanET B—Nannosquillidae dorsal view (G). Flying Saucer type: LyET A—ventral (H) and dorsal (I) views. Spiny balloon type: LyET B—ventral (J) and dorsal (K) views. Close up of Rocket types: NanET A (L) and NanET B (M): dorsal (top), ventral (middle), and lateral (bottom) views. Scale bar of 10 mm applies to images A-K. Scale bar of 5mm applies to images L and M only. Antizoea larva of Lysiosquilla maculata with 1 mm scale bar; dorsal (top) and ventral (bottom) views (N).