Nannoniscus menziesi, MEZHOV, 1986

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 : 1034-1035

NANNONISCUS MENZIESI MEZHOV, 1986

( FIG. 6 )

M a t e r i a l e x a m i n e d: H o l o t y p e f e m a l e, Z M M U No. 6143.

Diagnosis: Body slender, length about 4.7 × pereonite 1 width; AI article 2 stout, length and width about 0.8 article 1 length and width; Mxp lateral margin devoid of setae; Mxp epipodite reaching upper third of palpal article 3; Md incisor teeth acute; pereonite 2 anterolateral tergites each with robust seta; Op with ventral posteriorly bent spine, posterior margin with numerous (≥ 18) long simple setae; Urp biramous, not projecting beyond Plt posterior margin; Urp exopodite short, length 0.3 protopodite length, endopodite length ≥ 5.4 exopodite length.

Redescription of female holotype: Habitus ( Fig. 6A ), only pereonites 6 and 7 and the pleotelson are illustrated. Pereonite 6 and 7 medially fused; pereonite 6 and 7 of similar width, pereonite 6 anterior margin strongly concave. Plt width equal to pereonite 6 width, width 0.9 length; posterior margin strongly rounded, anterior margin slightly concave. Urp not projecting beyond Plt posterior margin. AI ( Fig. 6C ) with five articles. First article circular and broadest, length 1.3 width, with two small simple setae and one broom seta (broken off) distally. Second article length 0.9 article 1 length, length 1.3 width, with two broom setae (one broken off) and one simple seta distally. Article 3 minute, length 0.1 article 1 length, length 0.3 width. Article 4 with long distal projection, article 4 (incl. projection) length 0.7 article 1 length, length 2.2 width, with one long broom seta and one simple seta (broken off) distally. Article 5 length 0.8 article 1 length, length 1.6 width, with one aesthetasc distally. AII ( Fig. 6B ), only podomere articles 2–5 illustrated. Articles 2–4 short, length of each article (2–4) ≤ 0.4 article 5 length; article 3 with one stout spine and one simple seta distally; article 4 with one small simple seta distally. Article 5 length 2.3 article 2 length, length 3.1 width, with one simple seta laterally. Md ( Fig. 6E, F ), Md palp of left and right mandible well developed, consisting of three articles almost reaching incisor. Palpal article 2 of lMd length twice article 1 length. Terminal article length about as long as article 1, tapering distally, with several (≥ 5) small setae ventrally. Palp of rMd similar to lMd with several (≥ 10) small setae ventrally, with three somewhat longer setae distally. Incisor process of lMd with seven teeth, incisor of rMd with four teeth. Lacinia mobilis of lMd with four teeth. Spine row of lMd with 12 robust spines of varying size and several slender setae in between; dentation decreasing and site increasing proximally. Spine row of rMd with 11 robust spines and several slender setae in between, dentation decreasing, seta size increasing proximally. Molar of rMd and lMd triangular; molar of rMd with 16, of lMd with 12 long, serrate spines distally. PI ( Fig. 6H ), damaged between basis and ischium. Basis length 3 width, with one simple seta ventrally. Ischium length 0.6 basis length, length 1.6 width. Merus quadrangular, length 0.6 ischium length, as long as wide. Carpus length 2.1 merus length, length 2.6 width, with three unequally bifid setae and two long simple setae ventrally. Propodus length 0.6 carpus length, length about twice width, with one simple setae dorsally, with numerous small setae, membranously embedded, and two setae (one simple, one unequally bifid) in between ventrally, with one long simple seta distoventrally. Dactylus length 0.6 propodus length, length 3 width, with three slender setae medially. Unguis length 0.4 dactylus length, with two long, slender setae between unguis and ventral claw. Op ( Fig. 6F ) length 1.2 width. Lateral margin rounded, posterior margin almost straight, with several (≥ 18) simple setae, seta length 0.2 Op length, medial two setae somewhat shorter, length 0.1 Op length. Urp ( Fig. 6G ) biramous. Protopodite with one long simple seta laterally. Exopodite minute, length 0.3 protopodite length, with two simple setae terminally. Endopodite length 5.4 exopodite length, length 3.2 width, with five setae terminally (all broken off) .

Remarks: The anterior part of the specimen was damaged, thus only drawings of the posterior somites were made. These clearly show a lack of articulation between pereonites 6 and 7, which is not obvious in Mezhov’s (1986) drawings. Examination of the original slides did not reveal a ventral spine on the operculum, nor damage of the tissue. However, the setation pattern corresponds to Mezhov’s illustrations, suggesting that slides did not get mixed up. It remains to be proven that N. menziesi possesses a ventral opercular spine.

Figures

Figure 6. Nannoniscus menziesi Mezhov, 1986, holotype female (ZMMU 6143): (A) habitus, posterior somited, dorsal view; (B) AII; (C) AI; (D) rMd; (E) lMd; (F) Op; (G) Urp; (H) PI. Scale bars: A–H = 100 µm.