Nannoniscus ovatus, MENZIES & GEORGE, 1972

Kaiser, Stefanie, Kihara, Terue Cristina, Brix, Saskia, Mohrbeck, Inga, Janssen, Annika & Jennings, Robert M., 2021, Species boundaries and phylogeographic patterns in new species of Nannoniscus (Janiroidea: Nannoniscidae) from the equatorial Pacific nodule province inferred from mtDNA and morphology, Zoological Journal of the Linnean Society 193, pp. 1020-1071 : 1035-1037

NANNONISCUS OVATUS MENZIES & GEORGE, 1972

( FIG. 7A–F )

Material examined: Holotype, male, USNM Cat. No. 121022; allotype female (Vema.U-15–69), under the same accession number as the holotype.

Diagnosis: Body slender, length about 4.9 × pereonite 1 width; Mxp lateral margin devoid of setae; Mxp epipodite reaching proximal third of palpal article 3; pereonite 2 anterolateral tergites each with robust seta; pereonite 7 lacking ventral spine; Op with ventral posteriorly bent spine, posterior margin with ≤ nine simple setae; Urp uniramous, not projecting beyond Plt posterior margin; male PlpI with three hook-like projections distally.

Redescription of male holotype: Habitus ( Fig. 7D–F ), body length 4.9 × pereonite 1 width. Coxae not visible in dorsal view. Cephalothorax ( Fig. 7D ) length 0.9 width. Anterior and lateral margins straight, posterior margin slightly rounded. Antennae inserting frontolaterally in deep fold. Pereonites 1 and 2 of equal width, pereonites 2–7 decreasing in width; pereonite 1 length 0.3 width. Pereonite 2 length 1.4 pereonite 1 length, length 0.5 width. Pereonites 2 and 3 of similar length; pereonite 4 length 1.5 pereonite 1 length. Pereonites 1–4 anterior margins frontally directed, rounded; anterolateral tergites of pereonite 2 each tipped with robust seta. Pereonite 5 length 1.2 pereonite 1 length, anterior margin straight. Pereonites 6 and 7 dorsomedially fused, pereonite 6 anterior margin strongly convex. Plt length 0.2 body length, length 1.4 width, width 0.8 pereonite 1 width; posterior margin strongly rounded; anterior margin convex. Urp ( Fig. 7F ) drawn in situ. Uniramous, length 0.3 Plt length, not projecting beyond posterior margin. Protopodite length 1.4 width. Endopodite length 1.4 protopodite length, length 4.4 width.

Description of female paratype: Habitus ( Fig. 7A–C ), body length 4.7 × pereonite 1 width. Coxae not visible in dorsal view. Cephalothorax ( Fig. 7A ) length 0.9 width. Anterior and lateral margins straight, posterior margin slightly rounded. Antennae inserting frontolaterally in deep fold. Op ( Fig. 7B, C ) length 1.4 width, with strong ventral spine, posteriorly bent. Lateral and posterior margins rounded, posterior margin with several (≤ 9) short simple setae. Pereonites 2–7 decreasing in width; pereonite 1 and 2 widest, pereonite 1 length 0.3 width, pereonite 2 length 0.4 width, length 1.5 pereonite 1 length. Pereonite 3 longest, length 2.1 pereonite 1 length. Pereonites 2, 4, 6 and 1, 5 and 7 of similar length. Pereonites 1–4 anterior margins frontally directed, rounded, anterolateral tergites of pereonite 2 each tipped with robust seta, tergites of pereonites 3 and 4 each with small simple seta. Pereonite 5 width 0.8 pereonite 1 width, its anterior margin slightly concave, pereonite 6 anterior margin strongly convex. Pereonites 6 and 7 fused. Plt length 0.2 body length, length 1.4 width, width 0.7 pereonite 1 width tapering towards distal end; posterior margin strongly rounded, anterior margin convex. Urp ( Fig. 7C ) drawn in situ. Uniramous, length 0.2 Plt length, not projecting beyond Plt posterior margin. Protopodite length 1.4 width, with three simple setae laterally. Endopodite length 1.1 protopodite length, length 4.5 width, with few simple setae terminally.

Remarks: Menzies & George (1972) did not provide a description of the female of N. ovatus . Yet, owing to gender-related dimorphism also known from nannoniscids ( Wilson, 2008), both sexes are required for morphological comparison.

Figures

Figure 7. A–C,Nannoniscus ovatus Menzies & George, 1972, allotype female (USNM 121022); (D–F) holotype male (USNM 121022); (G–I) N. perunis Menzies & George, 1972, holotype female (USNM 121017–121018): (A) habitus, dorsal view; (B) Plt and Op, lateral view; (C) Plt and Op, ventral view; (D) habitus, dorsal view; (E) Plt, lateral view; (F) Plt, ventral view incl. Urp.; (G) habitus, dorsal view; (H) Plt, ventral view; (I) Urp. Scale bars: A, G–I = 100 µm; B–F = 200 µm.