Adlafia tjibaoui Le Cohu, Marquié & Coste, 2018

Marquie, Julien, Cohu, Rene Le & Coste, Michel, 2018, Adlafia moseri and A. tjibaoui two new diatom species (Bacillariophyta) from New Caledonia with further observations on Adlafia muscora and Kobayasiella saxicola, Phytotaxa 357 (1), pp. 41-51 : 45

Adlafia tjibaoui Le Cohu, Marquié & Coste sp. nov. ( Figs 19−28 )

LM ( Figs 19−24 ): Valves linear with narrowly rostrate apices in larger specimens and shortly protracted, rounded apices in smaller individuals. Valve dimensions (n=25): length 8.5−14.5 μm, width: 3.0−3.5 μm, ratio length/width 2.9−4.3. Axial area linear. Raphe hardly visible in LM. Striae not discernible in LM.

SEM ( Figs 25−28 ): Axial area narrow, less than 1/8 of total valve width, linear throughout entire length ( Fig. 25 ). Striae, 42−44 in 10 μm, composed of externally occluded, quadrangular areolae ( Figs 25, 26 ), clearly radiate between center and Voigt faults, convergent thereafter ( Figs 27, 28 , arrows). Two shortened striae present in central area ( Fig. 27 ). External raphe branches slightly curved. Proximal raphe endings deflected to primary side ( Figs 25, 26 ). Terminal raphe fissures strongly bent to secondary side, not extending onto valve mantle ( Fig. 26 ). Internally, raphe fissures straight, proximal raphe endings shortly deflected towards primary side, distant from each other. Distal raphe endings terminating onto small helictoglossae ( Figs 27, 28 ).

Type: —Tade: municipality of Ouegoa, NEW CALEDONIA. (20.404517° S, 164.453733° E), benthic periphyton, Julien Marquié, June 2013 (holotype: PC! slide no. 01455191, isotype: BR! Slide no. 4482).

Etymology: —The new species is dedicated to Mr. Jean− Marie Tjibaou, defender of the rights of the native Kanak people of New Caledonia.

Distribution and ecology: — Adlafia tjibaoui was only observed in the Panié massif region, in the north of New Caledonia, outside the ultramafic area (i.e., on volcano-sedimentary substrates). The area is famous for its highly endemic flora and fauna ( Tron et al. 2013). Little is known about the water chemistry of this region except that the water is poor in nutrients with a very low specific conductance ( Weninger 1968). The major accompanying taxa include Gomphonema lagenula Kützing (1844: 85) , Encyonema silesiacum (Bleisch in Rabenhorst 1861–1882, no. 1802) D.G.Mann (1990: 667), Achnanthidium sp. ( A. aff. catenatum ( Bily & Marvan 1959: 34–35) Lange-Bertalot (1999: 277) . Due to possible misidentification in LM with other Adlafia species, the occurrence of the taxon is not clearly known.

Figures

FIGURES 19−24. Adlafia tjibaoui sp. nov., type material from New Caledonia. Valves showing the variation in valve outline and size, LM. Scale bar = 10 μm.

FIGURES 25−28. Adlafia tjibaoui sp. nov. SEM. Fig. 25. External view of an entire valve showing the stria pattern and the curved raphe branches. Fig. 26. External view showing the terminal fissure not extending on the mantle. Fig. 27. Internal view of a valve showing the linear axial area, the quadrangular areolae and the Voigt faults (arrows). Fig. 28. Detail of Fig. 27 showing the proximal raphe endings curved to the primary side of the valve and Voigt fault (arrow). Note the shortened striae around the central area. Scale bar = 2 μm.