Quadrellinae Števčić, 2005

Ng, Peter K. L., Ahyong, Shane T. & Castro, Peter, 2023, Re-appraisal of the families and subfamilies of Trapezioidea Miers, 1886, with establishment of a new family, Ectaesthesiidae (Crustacea: Decapoda: Brachyura), Raffles Bulletin of Zoology 71, pp. 606-631 : 620-621

publication ID	https://doi.org/ 10.26107/RBZ-2023-0047
publication LSID	lsid:zoobank.org:pub:821BC4EC-5AF9-4727-84A3-C44839DFBE28
persistent identifier	https://treatment.plazi.org/id/038EC92D-797C-7E51-FC2E-6C452733F782
treatment provided by	Felipe
scientific name	Quadrellinae Števčić, 2005
status

Treatment

Subfamily Quadrellinae Števčić, 2005

Quadrellini Števčić, 2005: 41.

Diagnosis. Carapace hexagonal, slightly wider than long; antero- and posterolateral margins clearly demarcated, anterolateral margin with 2 sharp spines (excluding sharp external orbital spine) ( Fig. 11B View Fig ); front spinate to denticulate; posterolateral margin distinctly almost straight to gently convex ( Fig. 11B View Fig ); carapace relatively low, dorsal surface flattened, gently convex in frontal view; posterior margin of epistome with median lobe distinct, lateral margin relatively short, gently concave, with 2 low triangular lobes, separated by cleft from pterygostomial lobe ( Fig. 11C View Fig ). Basal antennal article quadrate, mobile, peduncle entering hiatus of orbit or orbit closed ( Quadrella ). Maxilliped 3 merus quadrate, slightly longer than wide, transversely narrower, shorter than trapezoidal ischium at midlength ( Fig. 6C View Fig ). Chelipeds long, slightly heterochelous to homochelous, major cheliped length about twice or more carapace width; merus elongated, slender, with sharp spines or denticles on flexor margin (only granules in Hexagonaloides ); carpus inner angle with or without spine ( Fig. 11B View Fig ). P2–5 very long, longest pereopod about twice carapace width; merus slender, elongated; dactylus facial surfaces with transverse comb-like rows of feeding setae ( Fig. 11B, D View Fig ). Male thoracic sternum wide, with sternopleonal cavity reaching anteriorly to level of midlength or anterior margin of P2 coxae ( Fig. 7D View Fig ); male thoracic sternites 2, 3 suture shallow, sometimes indistinct ( Fig. 7D View Fig ); tubercle of male pleonal-locking mechanism distinct, on anterior one-third of thoracic sternite 5 or on its posterior edge near suture with sternite 6 ( Fig. 8I View Fig ). Male pleon broadly triangular to narrowly linguiform; lateral margins of somites 3–6 converging; somites 3–5 fused with sutures undiscernible medially ( Figs. 7D View Fig , 8C View Fig ). G1 relatively slender, with distal portion gently curved; distal margins lined with long or short spinules ( Fig. 9G View Fig ). G2 about one-third length of G1 ( Fig. 9H View Fig ). Vulva ovate, opening directed inwards, with hard lateral sternal vulvar cover arching over narrowly ovate membrane-covered opening; vulvae positioned on submedian part of sternite 6 ( Fig. 10D View Fig ).

Genera included. Hexagonalia Galil, 1986b , Hexagonaloides Komai, Higashiji & Castro, 2010 , and Quadrella Dana, 1851b .

Remarks. As noted above, Hexagonaloides , originally thought to differ from other quadrellines by the apparent absence of the comb-like rows of feeding setae on P2–5 ( Komai et al., 2010), is now known to have such setae. As such, Quadrellinae now forms a well-defined group within Trapeziidae connected by similar overall habitus and potentially similar biology, assuming that the setation of P2–5 is related to mucus-gathering feeding given that a potential symbiotic association with a cnidarian or any other host remains unknown.

Quadrellines have been reported from antipatharians, alcyonaceans, gorgonians and azooxanthellate (ahermatypic) scleractinian corals ( Castro, 2015).