Caecianiropsis Menzies & Pettit, 1956

Kim, Jeongho, Lee, Wonchoel & Karanovic, Ivana, 2019, A new interstitial species of the genus Caecianiropsis Menzies & Pettit, 1956 (Isopoda, Asellota) from Korea, ZooKeys 832, pp. 35-56 : 37-38

Genus Caecianiropsis Menzies & Pettit, 1956

Austroniscus Vanhöffen, 1914: 553; Branch et al. 1991: 28.

Caecianiropsis , Menzies and Pettit 1956: 441; Kensley 1976: 295; Kussakin 1979, 1988: 160; Wilson 1994: 751; Wilson and Wägele 1994: 693.

Type species.

Caecianiropsis psammophila Menzies & Pettit, 1956

Included species.

C. birsteini Kussakin, 1979, C. ectiformis ( Vanhöffen, 1914)

Generic diagnosis.

(modified from Wilson and Wägele 1994)

Body six times longer than wide; cephalon with no eye, weakly developed rostrum reaching to middle of antennular article I; pleonite I 0.8 times wider than pereonite VII; pleotelson as wide as pereonite VII; antennula with V‒VII articles, antennal article III with rudimentary scale laterally; mandibular molar process truncate, palp article II medially swollen, with 2‒3 robust setae, median setigerous margin slightly depressed; maxillipedal endite two times longer than wide, distomedially pointed; medial lobes of male pleopod I distally rounded, distolateral edge of hyaline lamella projected; exopod of male pleopod II inserting subdistally on sympod, endopod proximally expanded, appendix masculina more than four times longer than sympod, coiled in relaxed position; endopod of pleopod III with three distal broom setae having distinct gap between medial seta and two lateral setae.

Remarks.

Wilson and Wägele (1994) provided a simple note on the morphological affinity between Caecianiropsis and Neojaera emphasizing a coiled, very much elongate stylet of male pleopod II in male. The major differences between Neojaera and Caecianiropsis are the presence of distinctly developed uropods showing the elongate sympod, and the much longer endopod in Caecianiropsis . In addition, the development of rostrum is also a noticeable difference between the two genera, with Caecianiropsis having an elongated rostrum reaching to the middle of the antennular article I, and its width is almost the same as antennula article 1, while Neojaera has only a weak anterior protrusion on the rostrum. Other morphological differences between the two genera are as follows: 1) cephalon without visual organ; 2) length of the cephalon as long as its width; 3) all pereonites almost same in length; 4) antenna much longer than antennula (more than twice); 5) lateral margin of the male pleopod I extended, angular form; 6) sympod of the male pleopod II, 2.6 times longer than wide. Wilson and Wägele (1994) also found several similarities between Caecianiropsis and Microjaera Bocquet & Levi, 1955 including the body form, antennal articulation, and male pleopod II with the elongate and coiled stylet. However, the elongation of the body can be a result of adaptation to the interstitial environment and therefore often evolve convergently. In addition, similar antennal articulation can be found in many other isopod groups. This similarity is also only superficial because Caecianiropsis shows a rudimentary scale on article III of antenna, which is lacking in Microjaera . On the other hand, elongation of the male stylet is one of the most noticeable characters of Caecianiropsis within the family Janiridae . Although, Wilson and Wägele (1994) mentioned that Microjaera anisopoda Bocquet & Levi, 1955 also possesses a similar morphology of male pleopod II, the original description of this species was limited due to the poor illustration of this particular character. Shimomura (2005) described another species, Microjaera morii Shimomura, 2005, but based on non-ovigerous female only; therefore this important male character is missing. Phylogenetic analysis of Janiridae ( Wilson 1994) based on 33 morphological characters suggested a close relationship between Caecianiropsis and the Microjaera . However, this has to be considered with caution because the important male characters are not well described in the latter genus.