Diastylis insularum ( Calman, 1908 )

Gerken, Sarah, 2015, New Zealand Diastylidae and Gynodiastylidae (Crustacea: Cumacea), Zootaxa 4031 (1), pp. 1-77 : 38

Diastylis insularum ( Calman, 1908)

Leptostylis (?) insularum Calman, 1908: 234 –239.

Diastylis insularum . — Calman, 1911: 342, 358.— Jones, 1963: 56 –57. Diastylopsis insularum . — Stebbing, 1913: 114.

Material examined. None.

Diagnosis. Female and subadult male. Carapace elongate, carapace, pereon and pleon covered with tiny spines, carapace with row of larger spines parallel to posterior margin just behind frontal lobe suture; ventral margin smooth; antennal notch present. Eyelobe without lenses. Pseudorostrum acute, 0.25 times carapace length anterior of eyelobe. Antennule article 2 longer than article 3. Maxilliped 3 ischium produced as large lobe laterally. Pereopod 1 basis ischium merus together equal to carpus propodus dactylus together, carpus shorter than propodus, propodus longer than dactylus. Pereopod 2 carpus 4 times propodus length. Pereopods 3–4 with rudimentary exopods in female. Telson with 9 lateral setae, more than 0.5 times length of uropod peduncles.

Adult male. Carapace similar to female, but carapace, pereon and pleon lacking tiny spines, row of larger spines is more obvious. Pereonite 5 is produced sharply posteriorly. Antenna extends past uropods. Telson dorsally produced.

Remarks. The line of moderately sized spines on the carapace, parallel to the posterior margin and originating posterior of the frontal lobe suture, present in both males and females, is distinctive in the New Zealand fauna.