Nannoniscus hilario, 2021

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 : 1037-1042

NANNONISCUS HILARIO KAISER & KIHARA , SP. NOV.

( FIGS 8–10 )

Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 02A15862-0D93-40B4-BD9A-0F41E6D70CA6.

Type fixation: Holotype, preparatory female, ZMH K-55342, 3.6 mm, designated here.

Material examined: Holotype: female (preparatory, Na 23), 3.6 mm, CCZ, equatorial NE Pacific, JPIO SO239 expedition, RV Sonne, EBS, station 24 (start: 11°51’19’’N, 117°1’30’’W, 4093 m; end: 11°51’31’’N, 116°58’0’’W, 4093 m), date: 22/03/2015, ZMH K-55342.

Paratypes: Preparatory female (Na 25), same location as holotype, ZMH K-55381; preparatory female ( NB12 _Iso020), CCZ, equatorial NE Pacific, BIONOD expedition, RV L’Atalante, EBS, station 06 (start: 11°46’13’’N, 116°41’8’’W, 4259 m; end: 11°46’13’’N, 116°41’7’’W, 4259 m), date: 02/04/2012, ZMH K-55341 .

Etymology: The new species (noun in apposition) is named after Ana Hilario for her support and enthusiasm to join the SO239 ‘Berta’ team (in this case down to 4259 m).

Distribution: Only known from the type locality (German licence area, eastern CCZ), between 4093 and 4259 m depth.

Diagnosis: Body slender, length about 5.5 × pereonite 1 width; Mxp lateral margin with numerous small setae; Mxp epipodite reaching distal third of palpal article 2; molar process of both Md with ≥ nine distal spines each; Md incisor teeth rounded; pereonite 2 anterolateral tergites each with robust seta; pereonite 7 without ventral spine; Op with ventral posteriorly bent spine, posterior margin with several (≤ nine) long simple setae; Urp biramous, not projecting beyond Plt posterior margin; Urp exopodite minute, endopodite length ≥ 6.3 exopodite length.

Description of holotype and paratype female: Habitus ( Figs 8A, E , 10 ), body length 5.5 pereonite 1 width. Coxae not visible in dorsal view. Cephalothorax ( Figs 8A, E , 10D–E ) almost as long as wide. Anterior and lateral margins straight, posterior margin slightly rounded. Antennae inserting frontolaterally in deep fold. Pereonites 1–4 of similar height, abruptly flattening from pereonite 4 to 5. Pereonites 1 and 2 of similar width, gradually decreasing in width from 2 to 7; pereonite 1 length 0.3 width. Pereonite 2 length 1.3 pereonite 1 length, length 0.4 width. Pereonite 3 length 1.8 pereonite 1 length; pereonite 4 length 1.7 pereonite 1 length. Pereonites 1–4 anterior margins frontally directed, anterolateral tergites of pereonite 2 each tipped with robust seta, anterolateral tergites of pereonites 3–4 each tipped with simple seta. Pereonite 5 longest, length 1.9 pereonite 1 length, anterior margin straight. Pereonites 6–7 dorsomedially fused; pereonite 6 anterior margin convex. Plt length 0.2 body length, length 1.2 width, width 0.9 pereonite 1 width; posterior margin strongly rounded; anterior margin slightly concave. Urp length 0.3 Plt length, not projecting beyond posterior margin. AI ( Fig. 8B ) length 0.1 body length, with five articles. First article length 2.3 width, with one small broom seta and one simple seta distally. Second article length 0.7 article 1 length, length 1.4 width, with two broom setae (broken off) and one simple seta distally. Article 3 minute, length 0.1 article 1 length, length 0.3 width. Article 4 length 0.2 article 1 length, with long distal projection reaching mid of article 5, with one small broom seta distally. Article 5 slightly damaged, length 0.7 article 1 length, length 2.5 width, with one aestetasc (?, broken off) terminally. AII ( Fig. 8B ) broken off, only podomere articles 1–4 present; articles quadrangular of similar length and width. Md ( Fig. 8C, D ), palp of left mandible well developed (in rMd broken off), consisting of three articles almost reaching incisor. LMd palpal article 2 length 1.5 article 1 length. Terminal article length 0.3 article 2 length, tapering distally, with two setae distally. Incisor process of rMd with four rounded teeth, incisor of lMd with two rounded teeth. Lacinia mobilis of lMd with three teeth. Spine row of rMd with nine robust spines increasing in size proximally. Spine row of lMd with eight robust spines and several slender setae in between, dentation decreasing, seta size increasing proximally. Molar of rMd and lMd triangular; molar of rMd with 10, of lMd with nine serrate spines distally. Mxp ( Fig. 8F ), left and right Mxp connected by two retinacula. Epipodite smooth, triangular, slender, length 4 width, reaching distal third of palpal article 2. Palpal article 1 short, width 0.3 length, with several small setae laterally. Article 2 length 3 article 1 length, width 1.1 length, with several small setae laterally, with one simple seta distally. Article 3 length 3 article 1 length, width 0.9 length, with two robust sensory setae distally with one simple seta laterally. Article 4 length 1.1 article 1 length, width 0.5 length. Article 5 length 0.6 article 1 length, width 0.5 length, with five slender setae of varying size terminally. Endite distal margin with some robust setae and several fine setae laterally. Basis triangular, length 0.9 width. PI ( Fig. 9C ) basis length 2.7 width. Ischium 0.6 basis length, length about twice width. Merus length 0.7 ischium length, length 1.5 width, with two long simple setae distodorsally, with one small simple seta distoventrally. Carpus length 1.7 merus length, length 2.5 width, with three unequally bifid setae, increasing in size distally, and one simple seta ventrally. Propodus length 0.7 carpus length, length 2.3 width, with numerous small setae, membranously embedded ventrally, and one robust unequally bifid seta and one simple seta distoventrally. Dactylus length about half propodus length, length 2.9 width. Unguis length 0.9 dactylus length, with two long, slender setae underneath unguis. PII ( Fig. 9D ) basis length 3.5 width, with one seta (broken off) ventrally. Ischium length about half basis length, length twice width, one long simple seta distodorsally. Merus length 0.9 ischium length, length 1.6 width, with one robust simple seta distodorsally, with one slender simple seta distoventrally. Carpus length 1.9 merus length, length 3.6 width, with one simple seta distodorsally, with row of four unequally bifid setae ventrally, increasing in size distally. Propodus length 0.7 carpus length, length 4 width, with one long simple seta distodorsally, with numerous small setae, membranously embedded ventrally, with one small unequally bifid seta distoventrally. Dactylus length 0.4 propodus length, length 3 width, with numerous small setae, membranously embedded ventrally. Unguis length about half dactylus length, with one slender seta between unguis and ventral claw. PIV ( Fig. 9E ) slightly damaged between ischium and merus. Basis length 4.8 width, with one short simple seta and one long broom seta dorsally. Ischium length half basis length, length 2.5 width, with two small simple setae dorsally. Merus length 0.6 ischium length, length 1.9 width, with one simple seta distodorsally, with two simple setae (one long, one broken off) distoventrally. Carpus length 2.2 merus length, length 4.7, with one unequally bifid setae (one broken off) ventrally. Propodus length 0.7 carpus length, length 4.8 width, with three long simple setae dorsally, with one slender simple and one stout unequally bifid setae ventrally. Dactylus length 0.3 propodus length, length 2.3 width. Unguis length 1.1 dactylus length, with two slender setae underneath unguis. PV ( Fig. 9F ) slightly damaged between basis and ischium. Basis length 3.3 width, with one simple seta dorsally, with two simple setae ventrally, with one long simple seta distoventrally. Ischium length 0.9 basis length, length 3 width, with one simple seta dorsally. Merus length 0.4 ischium length, length 1.6 width, with one long simple seta distodorsally, with one long simple seta ventrally, with one seta (broken off) distoventrally. Carpus length 2.3 merus length, length 3.5 width, with four long slender setae ventrally. Propodus length 0.7 carpus length, length 4 width, with five long simple setae dorsally. Dactylus length 0.4 propodus length, length 3.2 width. Unguis length 0.8 dactylus length, with two slender setae underneath unguis. Op ( Fig. 8G ) length 1.3 width, with strong ventral spine, posteriorly bent. Lateral margin and posterior margins rounded, with several (≤ nine) simple setae, setal length 0.2 Plt length. PlpIII ( Fig. 8H ), protopodite almost as long as wide, length about half endopodite length. Exopodite half endopodite length, length 2.3 width, tapering in width distally, with numerous short simple setae laterally and one somewhat longer seta distally. Endopodite length 1.6 width, with three long plumose setae distally, distal margin rounded. Urp ( Fig. 8J ) biramous, length 0.25 Plt length, not projecting beyond Plt posterior margin. Protopodite trapezoid, length 1.3 width, with one long simple seta laterally. Exopodite length 0.3 protopodite length, length twice width, with two simple setae terminally. Endopodite length 6.3 exopodite length, length 3.8 width, with two long simple setae and two long broom setae terminally.

Remarks: Nannoniscus hilario is most similar to species with a slender body (length ≥ 4.5 pereonite 1 width), biramous uropods and a ventral opercular spine, viz.: N. menziesi , N. meteori and N. perunis .

The new species can be distinguished from N. menziesi by the following characters: Mxp lateral margin with numerous small simple setae (vs. setae lacking in N. menziesi ); Op posterior margin with ≤ nine simple setae (vs. 18 setae); incisor teeth of left and right Md more rounded (vs. acute). Nannoniscus hilario also resembles N. meteori , but can be differentiated as follows: Mxp lateral margin with numerous small simple setae (vs. setae lacking in N. meteori ); Mxp endopodite reaching distal third of palpal article 2 (vs. mid of palpal article 3); Op posterior margin with ≤ nine simple setae (vs. 15 setae); Urp endopodite length 6.3 exopodite length (vs. 3.9). The new species can be furthermore differentiated from N. perunis by the following features: body length ≥ 5.5 pereonite 1 width (vs. ≤ 4.7 in N. perunis ); Urp endopodite length 6.3 exopodite length (vs. 7.8); pereonites 3–4 tergites each with an anterolateral seta (vs. setae lacking).

Figures

Figure 8. Nannoniscus hilario, (A, E, I) holotype female (ZMH K-55342, Na23); (B–D, F–H, J–K) paratype female (ZMH K-55341, NB12_Iso020): (A) habitus, dorsal view; (B) AI, peduncular articles 1–4 AII; (C) lMd; (D) rMd; (E) habitus, lateral view; (F) Mxp; (G) Op, ventral view; (H) PlpIII; (I) Plt, ventral view; (J) Urp; (K) Op, lateral view. Scale bars: A, E, I = 200 µm; B–D, F–H, J–K = 100 µm.

Figure 9. Nannoniscus hilario, (A–B) holotype female (ZMH K-55342, Na23); (C–F) paratype female (ZMH K-55341, NB12_Iso020): (A) habitus, dorsal view; (B) habitus, lateral view; (C) PI; (D) PII; (E) PIV; (F) PV. Scale bars: A–B = 200 µm, C–F = 100 µm.

Figure 10. Nannoniscus hilario, holotype female (ZMH K-55342, Na23). Confocal laser scanning microscopy images: (A) habitus, dorsal view; (B) habitus, lateral view; (C) habitus, ventral view; (D) mouthparts, ventral view; (E) cephalothorax, lateral view; (F) Plt, ventral view. Scale bars: A–C = 200 µm; D–F = 100 µm.