Frontohornera frontalis, Grischenko & Gordon & Melnik, 2018

Grischenko, Andrei V., Gordon, Dennis P. & Melnik, Viacheslav P., 2018, Bryozoa (Cyclostomata and Ctenostomata) from polymetallic nodules in the Russian exploration area, Clarion - Clipperton Fracture Zone, eastern Pacific Ocean-taxon novelty and implications of mining, Zootaxa 4484 (1), pp. 1-91: 29-32

publication ID

https://doi.org/10.11646/zootaxa.4484.1.1

publication LSID

lsid:zoobank.org:pub:D66524CF-9C6D-4DF4-8CA2-B2C9708CF5FD

persistent identifier

http://treatment.plazi.org/id/521587E4-562E-5518-09EE-F8FA884FF85C

treatment provided by

Plazi

scientific name

Frontohornera frontalis
status

n. sp.

Frontohornera frontalis   n. sp.

( Figs 2J, K View FIGURE 2 , 16–18 View FIGURE 16 View FIGURE 17 View FIGURE 18 )

Material examined. Holotype: ZIRAS 1/50707, colony detached from nodule, YMG R.V. Yuzhmorgeologiya

cruise YMG4–13, Stn 292, 27 July 2014, 13.03353° N, 132.49292° W, 4829 m. Paratype: ZIRAS 2/50708, colony attached to nodule particle, YMG R.V. Gelendzhik cruise GLD4–11, Stn 210, 20 April 2012, 13.35817° N, 133.27183° W, 4815 m. Additional material: YMG4–07, Stn 124; GLD4–11, Stn 215; YMG4–14, Stns 329, 334. Total specimens examined six.

Etymology. Latin, frontalis   , frontal, alluding to the frontally borne gonozooid.

Description. Colony erect, white, to 2.81 mm high, 6.76 mm broad, dichotomously branching once in a single plane ( Fig. 16A, B View FIGURE 16 ), or with short additional bifurcation to produce a third, short branch near colony center ( Fig. 18G, H View FIGURE 18 ). Stem diameter 0.32 × 0.37 mm, widening to colony base (0.66–0.76 mm). With distinct frontal and abfrontal faces ( Fig. 16 View FIGURE 16 ), entire surface interior-walled, textured irregularly with minute dimples, granules, ridges and furrows ( Fig. 17A –G View FIGURE 17 ), with longitudinal linearities only on stem of colony; conspicuous ribbing (nervi) and grooves (sulci) lacking. Pores simple, tiny, sparse.

Autozooids in 2–4 series, their peristomes produced frontally upwards, relatively short along frontolateral and central parts of branch, longest along abfrontolateral margin, with simple circular apertures, no apertural spines ( Fig. 17A –F, I View FIGURE 17 ). Peristomes somewhat dimorphic ( Fig. 17F View FIGURE 17 ), short and uniformly tubular with circular apertures in central face of branches, but strongly elongated, with aperture having shape of teardrop, isosceles triangle or irregular oval along branch margins. Peristome wall interiors with short, thin spinules proximal to aperture ( Fig. 17I View FIGURE 17 ). Cancelli most numerous on central part of branch distal to gonozooid ( Figs 16A View FIGURE 16 , 17A, E, J View FIGURE 17 ), otherwise sparse, shallow, of varying size. Abfrontal face of colony with outlines of autozooidal tubes ( Figs 16B View FIGURE 16 , 17G View FIGURE 17 ), their longitudinal contours converging proximad.

Gonozooid frontally borne, adjacent to second dichotomy ( Fig. 16A View FIGURE 16 ), subglobular, surface like that of colony but with slightly denser prickled granules ( Fig. 17H, J, K View FIGURE 17 ), frontal peak and distal sides of chamber converging towards short ooeciostome that curves frontalwards ( Fig.17H, J, K View FIGURE 17 ), ooeciopore transversely oval ( Fig. 17L View FIGURE 17 ).

Ancestrular zooid not seen in isolation; earliest growth stages encountered show lowest peristome of colony (presumed ancestrular peristome), which appears to be wholly erect, though concealed within basal skirt of extrazooidal calcification ( Fig. 18G, I View FIGURE 18 ). Peristome of daughter zooid above it in series, but in another colony ancestrular and two daughter peristomes occur as cluster of three ( Fig. 18B View FIGURE 18 ).

Measurements (mm). Holotype, ZIRAS 1/50707 ( Fig. 16A, B View FIGURE 16 ): ZL 0.569–0.763 (0.663 ± 0.071). Branch center: PeL 0.072–0.197 (0.122 ± 0.042); PeD 0.141–0.162 (0.153 ± 0.008); ApD 0.129–0.141 (0.137 ± 0.004). Branch margin: PeL 0.194–0.526 (0.374 ± 0.102); PeD 0.110–0.146 (0.135 ± 0.011); ApL 0.132–0.176 (0.156 ± 0.016) (n = 7); ApW 0.122–0.147 (0.132 ± 0.008) (n = 7). Gonozooid (n = 1): GZL 0.744; GZW 0.511; GZH = 0.377; OsL 0.167; OsW 0.132; OsH 0.196; OpL 0.073; OpW 0.071.

Non-type specimen GLD4–11, Stn 210 ( Fig. 18G –I View FIGURE 18 ): AnPeD 0.144 (n = 1).

Remarks. Frontohornera frontalis   n. sp. is represented in the collection by six colonies of varying ages and sizes. Only one reproductively mature colony was encountered. All were found attached to polymetallic nodules.

Distribution. Recorded from six stations within coordinates 13.03353– 14.29353° N, 131.87598– 134.23457° W, at depth range 4815–5166 m.