Geodia arma, Lehnert & Stone, 2019

Lehnert, Helmut & Stone, Robert P., 2019, Two new species of Geodiidae (Porifera, Demospongiae, Astrophorina) from the Emperor Seamounts, North Pacific Ocean, Zootaxa 4671 (3), pp. 381-395 : 389-393

Geodia arma n. sp.

( Figs. 4 & 5 ; Table 2 )

Material examined. Holotype MABIK IV00158487 , specimen dried, collected by Chano Hwang with a bottom trawl aboard the FV Oyang 96, 6 April 2014, 298 m depth, Koko Guyot , Emperor Seamounts, North Pacific Ocean (35° 20.202´N, 171° 32.598´E) . Paratypes MABIK IV00158489 , specimen dried, collected by Chano Hwang with a bottom trawl aboard the FV Oyang 96, 14 April 2014, 297 m depth, Koko Guyot , Emperor Seamounts, North Pacific Ocean (35° 28.800´N, 171° 23.202´E) ; MABIK IV00158492 , specimen dried, collected by Chano Hwang with a bottom trawl aboard the FV Oyang 96, 5 May 2014, 300 m depth, Koko Guyot , Emperor Seamounts, North Pacific Ocean (35° 18.300´N, 171° 29.502´E) .

Description. Three specimens of this semispherical sponge were collected and have diameters of 3.4–12 cm ( Figs. 4A, B , & C). The specimens examined are half spheres with one side covered by a thick cortex and the other side with the choanosome exposed ( Figs. 4B & C ); probably the sponges were broken when trawling them off the substrate, we suspect we only got the upper parts of the specimens. The cortex of sterrasters is 1.5–6 mm in diameter and consequently hard and inelastic ( Fig. 4C ). The surface is optically smooth but rough to the touch. One specimen has the surface partially covered with wart-like, slightly elevated apertures 2.5–4 mm in diameter ( Fig. 4A ). A second specimen has smaller apertures, 0.5–1mm in diameter. There are no other apertures visible, even when examined under a dissecting microscope.

Skeletal architecture. Choanosomal confused arrangement becomes radial towards the surface, the long oxeas reaching into the thick cortex of aspidasters ( Fig. 4D ).

Spicules. Megascleres are thin, sinuous ( Fig. 4F ) to thicker, almost-straight oxeas to strongyloxeas ( Fig. 4E ) in a wide size range, 280 to over 6000 x 16–42 µm. Long oxeas are mostly broken in spicule preparations so the lengths are hard to measure as one has to follow the course of the spicules in the slide preparations. Microscleres are oval sterrasters ( Figs. 4D , 5A, B, C ), 118–158–171 x 202–221– 243 µm, oxyasters with microacanthose rays ( Figs. 5D & E ), 18–20– 23 µm in diameter and, tylasters ( Figs. 5D & F ), 8–9– 11 µm in diameter.

Discussion. We compared the new species with all other species of Geodia lacking triaenes, a genus formerly referred to as Geodinella . The genus Geodinella was erected by Lendenfeld (1903, p. 117) for Geodia cylindrica Thiele, 1898 , a species with reduced triaenes, with the clads of triaenes reduced to two or less so that these spicules resemble diaenes, monaenes, styles or tylostyles. Uriz (2002) did not consider Geodinella as a valid genus and listed it among the synonyms of Geodia (p. 138) which is likely the reason why Van Soest et al. (2018) also regard Geodinella as a synonym of Geodia . However, Uriz (2002) in the same publication remarked regarding the genus Sidonops (p. 140) “Aborted triaenes as those in Geodinella have also been described in some species of Isops , Geo- dia, and Sidonops and, consequently, this character has no diagnostic value. As the inhalant orifices of Geodinella are uniporal and the oscula are cribriporal, this genus becomes synonymous of Sidonops .” So Uriz (2002) argued that Geodinella is synonymous with Sidonops but listed Geodinella among the synonyms of Geodia . The question regarding assignment of Geodinella to Geodia or Sidonops may be irrelevant when taking into consideration the publications of Cárdenas et al. (2010, 2011). Based on genetic sequences and morphological characters they suggest to synonymize the genera Geodia , Isops and Sidonops under Geodia . Consequently the characters uniporal/cribripo- ral apertures would lose their importance and Geodinella would either have to be regarded as a genus of its own or fall into synonymy with Geodia . It is not within the scope of this publication to rule on this issue so we follow the current scheme outlined in Van Soest et al. (2018). For recent reviews of the Geodiidae we refer to Cárdenas et al. (2010) and Sim-Smith & Kelly (2015). For the present study the “ Geodinella group” was helpful to detect species with reduced or no triaenes which we used to compare with the species described here.

Geodia arma is the only species which has oxeas which are over 6 mm in length and the width of the oxeas also includes thin, sinuous oxeas. It has the thickest cortex of all described species. The new species differs from compared congeners in the following characters ( Table 2 ):

G. cylindrica has only one category of oxeas (only half the length of the shorter oxeas of G. arma ), plagiomon- and -diaenes, smaller sterrasters, a considerably thinner cortex, and no oxyasters.

G. hyotania has only one category of oxeas, additional styles and subtylostyles, sterrasters are much smaller, the cortex is thinner, smaller spherasters than the oxeas of G. arma , and no tylasters.

G. isabella has two categories of oxeas (both approximately 1/10 th the size in G. arma ), sterrasters (approximately 1/7 th the size in G. arma ), a thinner cortex, two categories of oxyasters (one larger and the other smaller than those in G. arma ), and no tylasters.

G. lendenfeldi has oxeas which are blunt, additional styles, strongyles, tylotes and tylostyles, spicules which do not occur and which never reach the length of the oxeas and styles in G. arma . The width of monaxons of G. lendenfeldi are between 40–80 µm and are not sinuous while the monaxons of G. arma can be sinuous and are considerably thinner G. lendenfeldi has plagiomonaenes, ortho- and promonaenes which are completely missing in G. arma . G. Lendenfeldi has a thinner cortex.

G. spherastrosa has only one category of oxeas and additional reduced triaenes resembling tylostyles, smaller sterrasters, a thinner cortex, and larger oxyasters.

G. vestigifera has three categories of oxeas (none reaching the length of the thin, sinuous oxeas of G. arma ), triaenes resembling styles, smaller sterrasters, a thinner cortex, two categories of oxyasters (the larger category larger than those in G. arma ), strongylasters and strongylospherasters, and no tylasters.

Etymology. Named from the Latin arma—armour, referring to the unusual thick cortex of the new species.

Figures

FIGURE 4. Geodia arma n. sp. A, Holotype, upper surface. B, Basal-side of holotype. C, Paratype of Geodia arma, basal-side, showing extremely thick cortex and radial arrangement of choanosomal spicules towards the surface. D, Light microscopic sec- tion perpendicular to surface. Sterrasters at the upper margin belong to the cortex, long oxeas reach into the cortex from below. E, Long straight oxeon from upper left to lower right. F, Fragments of long, thin, sinuous oxeas among several sterrasters.

FIGURE 5. A, Developmental stage of sterraster with some oxyasters and tylasters on the surface. B, Adult sterraster With both types of asters on the surface C, SEM photo sterraster with the hilum visible at the narrow side. D, Surface rosettes of sterrasters with both types of asters. E, SEM photo of oxyaster, showing the microacanthose rays. F, SEM photo of tylaster.

Tables

TABLE 2. Spicule characteristics and locality of all known Geodia species that lack triaenes, formerly genus Geodinella Lendenfeld, 1903. All measurements are in µm unless otherwise noted.

Species, authority	Megascleres 1	Megascleres 2	Sterrasters & cor-	Oxyasters	Tylasters	Locality
			tex thickness
Geodia cylindrica	800– 1000 x 25–30	Plagiomon- and diaenes,	180 x 145 x 115,	None	7–8	Enoshima, Japan
Thiele, 1898 Geodia hyotania	Oxeas, 1500 –2300 x	same size as oxeas Styles and subtylostyles,	cortex ca. 300 thick 100–140 x 130–170,	Spherasters, 12–15	None	Sado Island,
( Tanita, 1965)	32–45	1300–2100 x 45 –55	cortex ca. 1 mm			Japan
Geodia isabella	Oxeas , 550 x 15	Oxeas, 100 x 3	thick 30 in diameter, cor-	Oxyspherasters, 30, ox-	None	Isabel Island,
( Dickinson, 1945) Geodia lendenfeldi	Blunt oxeas, also strong-	Plagiomonaenes, ortho-	tex 1 mm thick 180–237 x 130–200	yspherasters, 5 Oxyasters and oxyspherasters,	7–13	Sinaloa, Mexico Pacific Coast of
Stone et al., 2011	yles, styles, tylotes, tylo-	and promonaenes, rhabds,	x 80 –130, cortex 1–2	rays occasionally bifurcate at the		North America
	styles, 370–2500 x 40 –80	1100–2100 x 26–42, clades	mm thick	ends, ends microspined, 9–39 in
		30–105 long		total diameter, “size in inverse
Geodia spherastrosa	Oxeas, 2700 –3700 x	Triaenes resembling tylo-	170–180 x 150–160,	proportion to ray number” 25–35	8–9	Philippines
( Wilson, 1925)* Geodia vestigifera	60–70 Thick oxeas, 2000 x 120,	styles, 2400–2900 x 40 –60 Triaenes resembling styles,	cortex 1 mm thick 120 x 140, cortex	Large oxyasters, microspined	Strongylasters,	Spirits Bay,
( Dendy, 1924)	thin oxeas 1900 x 20, short	1400 x 25, rare anatriaenes	0.85 mm thick	rays, 64 in diameter, small ox-	24, strongy-	New Zealand
	oxeas, 480 x 17	(possibly foreign)		yasters (dimensions not provid-	lospherasters, 12
				ed), regarded as juvenile forms by
Geodia arma n. sp.	Sinuous, thin to almost-	None	118–171 x 202–243,	Dendy (1924) 18–23	8–11	Emperor
	straight, thick oxeas in a		cortex 1.5–6 mm			Seamounts,
	wide size range (280 to		thick			North Pacific
over 6000 x 16–42)

*: measurements from Lévi & Lévi, 1989