Quasiparalamprops, Gerken, 2018

Gerken, Sarah, 2018, The Lampropidae (Crustacea: Cumacea) of the World, Zootaxa 4428 (1), pp. 1-192 : 175-176

Quasiparalamprops n. gen.

Type species. Quasiparalamprops chathamensis n. gen., n. sp.

Diagnosis. Carapace dorsoventrally flattened, with marginal carina, eyelobe present, pseudorostral lobes short, blunt. Antennule flagella well developed, accessory flagellum at least 0.8 main flagellum. Maxillule palp present, entirely without setae. Pereopod 1 slender and long. Pereopod 5 shorter than or subequal to basis of pereopod 4. Telson with post–anal constriction, with 3 terminal setae. Uropods unknown. Female with fully developed exopod on pereopod 2, rudimentary exopods on pereopods 3–4, without pleopods. Male with antenna extending to posterior border of pereonite 4, without penial lobes, with 3 pairs of pleopods.

Etymology. The new genus is similar to Paralamprops and Platytyphlops in overall form, being dorsoventrally flattened with a marginal carina

Species. Quasiparalamprops chathamensis n. gen., n. sp.

Remarks. Quasiparalamprops is extremely unusual in that the maxillule palp is present, but apparently bears no setae. Among the telson bearing families, Diastylidae , Gynodiastylidae , Lampropidae and Pseudocumatidae , the absence of the maxillule palp is restricted to a few genera within the Lampropidae , as is the presence of a single seta on the maxillule palp. Quasiparalamprops is the first genus having a palp without setae. On the adult male paratype of Q. chathamensis , both maxillules were observed very closely at high magnification and neither setae nor setal bases (indicating broken setae) were observed on the palp. The maxillule of the female was not observed, because it could not be accessed without destroying the carapace of the holotype of Q. chathamensis , an unacceptable amount of damage to a holotype. While it is possible that this male is a single aberrant individual, there are no indications of aberrant development in the maxillule, the two endites are of the typical form with the typical arrangement and length of setae. It is unlikely that this is a sexually dimorphic difference, adult male mouthparts are typically similar or identical to functional mouthparts of the female. It is also unlikely that this is a case of end stage degeneration of mouthparts in the terminal male. Degenerate mouthparts have been observed in the ovigerous females of Atlantocuma Băcescu & Muradian 1974 and Pseudopicrocuma Akiyama 2012 ( Akiyama 2012) , but these are unusual cases, and degenerate mouthparts have never been reported in the adult male of any cumacean. In the case of Atlantocuma , the degeneration included decalcified mandibles, reduced setation on the maxilla, maxillules, maxilliped 1 and maxilliped 2, as well as slender maxillipeds 1 and 2, but the maxillule palp was still present and had 2 setae. In the case of Pseudopicrocuma , the degeneration included decalcified mandibles, reduced or lost setae on the maxillae and maxillules, and reduced setae on maxipellids 2 and 3, but the maxillule palp again was present and bore 2 setae.