Obruta collector, Turner & Lonhart, 2023

Turner, Thomas L. & Lonhart, Steve I., 2023, The Sponges of the Carmel Pinnacles Marine Protected Area, Zootaxa 5318 (2), pp. 151-194 : 185-188

Obruta collector sp. nov.

Figures 23 & 24

Material examined. Holotype: CASIZ236660 / IZC00048466 , La Jolla Cove, San Diego (32.85227, -117.27239), 10–16 m, 8/14/20 . Paratypes: Goalpost Reef , San Diego (32.69438, -117.26860), 12–15 m , 2/8/20; IZC00048464 , Isla Vista Reef , Santa Barbara (34.40278 -119.85755), 9–12 m , 8/1/19; IZC00048462 , Arroyo Quemado Reef , Santa Barbara (34.46775, -120.11905), 7–11 m , 6/14/19; SBMNH700907 , Arroyo Quemado Reef , Santa Barbara (34.46775, -120.11905), 7–11 m , 7/29/19; IZC00048465 , Whaler's Cove , Point Lobos, Carmel (36.52172, - 121.93894), 6–15 m , 11/23/19; SBMNH700924 , Otter Cove , Pacific Grove (36.62920, -121.92031), 7–12 m , 11/24/19; IZC00048463 , Inner Carmel Pinnacle (36.55852, -121.96820), 10–24 m , 9/22/21; SBMNH700915 , Goalpost , San Diego, (32.69438, -117.26860), 12–15 m , 2/8/20.

Etymology. "Debris collector," because the long protruding spicules tend to collect copious detritus in the habitats where it is found.

Morphology. A thickly encrusting sponge with upright lobes. Samples 3 mm to 2 cm thick; incompletely sampled individuals likely exceeded 4 cm in height. Color in life apricot (light yellow-orange); some samples variegated with peach and white; all samples beige when preserved. Surface is thick with protruding spicules, giving the sponge a furry appearance, often with sediment and debris ensnared on hispid surface.

Skeleton. Upright, slightly plumose bundles of oxeas, 5–10 spicules wide, project towards sponge surface, where they pierce the tissue and create a hispid surface. Many spicules also found outside of bundles; near sponge surface, these are mostly upright, adding to a generally plumose impression; near the sponge base, oxeas are found in utter confusion. Some megascleres found horizontally where sponge attaches to substrate; a minority of these have multiple bends resulting in a U or S shape and could be dubbed sinuous. No ectosomal specialization. No apparent spongin; spicules are unbound after proteinase K digestion. Spicule density is high; sponges are firm and incompressible.

Spicules. Oxeas, styles, and intermediates; sinuous oxeas.

Oxeas: slightly curved or straight; majority with sharp points at both ends, but minority have asymmetrical points, with one tip blunt or rounded; some of these approach styles. Holotype: 502–750-1208 x 5–14–31 μm (n=80). Dimensions vary greatly within and among samples. Average length was significantly associated with latitude (r 2 = 0.6, p = 0.02), but width was not (r 2 = 0.4, p = 0.08). Average lengths: San Diego samples = 750 and 747 μm; Santa Barbara samples = 743, 796, and 878 μm; Monterey samples = 932, 1138, and 1439 μm. All samples pooled: 477–948–2155 x 3–15–31 μm (n=360).

Styles: shaped like oxeas, but with one untapered, rounded end; less common than oxeas in all samples, with frequencies of approximately 1%–15%, depending on sample. Shorter than oxeas in all samples, with average lengths 75%–85% as long. Holotype: 521–612–729 x 8–12–15 μm (n=5); all samples pooled: 486–717–1321 x 5–12–23 μm (n=38).

Sinuous oxeas: oxeas with multiple bends and curves such that they are sinuous or U-shaped; some are only slightly sinuous and hard to differentiate from normal oxeas. Found in 5 of 8 samples. Holotype: 371–504–630 x 7–11–16 μm (n=12); all samples pooled: 231–510–1692 x 7–11–18 μm (n=43).

Distribution and habitat. Found on shallow subtidal reefs in Central and Southern California; not found in the intertidal or on human structures. Fairly common around Monterey and Carmel Bays, where it was found at 50% of subtidal reefs investigated. Less common in Southern California, where it was found at only 7% of subtidal reefs.

Remarks. Obruta collector sp. nov. is confidently placed in this nominal Bubarida clade at both loci, forming a subclade with Phakellia ventilabrum , type of its genus, and Axinellia cannabina (considered by some authors to be an Acanthella ( Gazave et al. 2010)) . The close evolutionary relationship of these three species highlights how difficult it will be to revise this order based on traditional characters. The two previously described species possess an axial skeleton of sinuous strongyles complemented by styles, and the new species possesses mostly oxeas. Phakellia ventilabrum is upright and fan-shaped, Axinella cannabina is branching and tubular, and Obruta collector sp. nov. is thickly encrusting and lobed.

The high spicule density, hispid surface, and basal skeleton of sinuous diactines of O. collector sp. nov. are consistent with placement in the Bubaridae , and not consistent with the other bubarid families ( Dictyonellidae and Desmanthidae ). However, none of the existing genera placed within the Bubaridae , nor other genera that may be included in the Bubarida after revision, are a good fit for O. collector sp. nov. The close relationship of this new species to the type species of Phakellia is intriguing, but that genus is currently defined by its planer habit, multiple axes of sinuous strongyles, and styles, none of which are possessed by O. collector sp. nov. The genus Bubaris is more similar to the new species, as it is encrusting with sinuous diactines along the substrate. However, Bubaris is defined by having sinuous strongyles and styles, a thinly encrusting habit, and a skeleton of single styles erect on the substrate. Though some species currently placed in this genus have other growth forms (e.g., B. sarayi Ilan e t al. 1994, B. conulosa Vacelet & Vasseur 1971 ), they all possess only sinuous strongyles and styles. As O. collector sp. nov. possesses primarily oxeas and is thickly encrusting, we deem it necessary to create a new genus to house this species. The presence of sinuous diactines and lack of an ectosomal skeleton are morphological characters that unite this species with most other members of the Bubarida and other species that will likely be revised into the genus based on the phylogenies shown.

Obruta collector sp. nov. can be easily differentiated from other named species, as evidenced by the need to create a new genus to house it. Due to the ill-defined boundaries of some genera of Bubarida , Axinella , and Halichondriidae , however, it is worth listing the similarities and differences of species from several other genera that occur in the North East Pacific. The only previous Bubarida known from the region is Rhaphoxya laubenfelsi Dickinson, 1945 from Pacific Mexico. This species is differentiated by being ramose and branching, possessing sharply bent styles, and being green after preservation. Two Axinyssa are known from the northeast Pacific, and some members of this genus have genetic affinities to the Bubarida . Axinyssa tuscara ( Ristau, 1978) is sympatric with O. collector sp. nov., but is dark brown with smaller oxeas. Another species from Pacific Mexico, Axinyssa isabela Carballo & Cruz-Barraza, 2008 , has similar spicules and a somewhat similar skeleton to O. collector sp. nov., but is yellow, sprawling, and is not macroscopically hispid.

Young or small individuals of this species may be difficult to identify in the field, but larger individuals have a distinctive combination of growth form, color, and very hispid surface. All individuals of this form were correctly identified to species before verification with spicules and DNA sequencing, and no other samples were erroneously assigned to this species, so tentative field identifications are likely to be fairly reliable with experienced observers. Individuals from this species from Southern California were the focus of recent research on terpene biosynthesis in sponges ( Wilson et al. 2023).

Figures

FIGURE 23. Maximum likelihood phylogenies for the Bubarida. A: 28S locus, B: cox1 locus. Green clade designated the putative Bubarida; the orders and families currently housing each taxon is also shown. Genbank accession numbers are shown; bold indicates new sequences; asterisks designate type species. Node confidence is based on bootstrapping. Scale bar indicates substitutions per site. Colors indicate clades containing new taxa, as referenced in the text.

FIGURE 24. Obruta collector. Field photos of IZC00048463 (A) and holotype (B). Leucilla nuttingi sample IZC00048456 visible as small calcareous growths on O. collector in A. C: cross-section at surface of sponge, from holotype. D: Cross-section at base of sponge, from TLT522. E: style from SBMNH700907. F:Anisoxea from SBMNH700907. G: oxea from IZC00048464. H–J: sinuous oxeas. H,I from holotype, J from SBMNH700924.