Neosiphonia microtriaeneae, Gómez & Calderón-Gutiérrez, 2020

Gómez, Patricia & Calderón-Gutiérrez, Fernando, 2020, Anchialine cave-dwelling sponge fauna (Porifera) from La Quebrada, Mexico with the description of the first Mexican stygobiont sponges, Zootaxa 4803 (1), pp. 125-151 : 141-143

Neosiphonia microtriaeneae sp. nov.

Figs. 10-11

Material examined. HOLOTYPE CNPGG‒1487 Cenote S-1, La Quebrada anchialine cave, Cozumel, Quintana Roo, Mexico (20°26’16.75’’N, 86°59’47.44’’W). Depth 5.2 m, October 23, 2015; coll. F. Calderón-Gutiérrez and German Yáñez. PARATYPES CNPGG–1483, same locality as holotype, 4.5 m depth, January 12, 2015 . CNPGG– 1486 same locality, 5.6 m depth, October 25, 2015; coll. F. Calderón-Gutiérrez and German Yañez.

Description. Spherical to oval shaped with a slightly restricted base, overall size 10‒13 mm long, 9‒12 mm wide, 8 mm high, round and deep apical oscula on top, 1.0‒ 2.5 mm ( Fig. 10a ). Color chestnut brown when alive, turning pale when in alcohol. Surface rough, due to the microtriaenes protruding outside the surface. Longitudinal canals are shown over the surface and some converge to the oscule. Consistency hard, brittle and rough to the touch, it crumbles easily when touched.

Skeleton. ( Fig. 10 b-c) The ectosomal skeleton consists of tetraclone desmas along with scattered trichotrianes; embedded with the rhabdomes toward the choanosome, and cladomes parallel to the surface. Choanosomal skeleton is made up of desma tetraclones and some smooth ones, probably young stages. Abundant oxeas as well as microsclere spicules fill out the interstices among desmas.

Spicules. ( Fig. 11 a-i) Tetraclone desmas with smooth clones, and irregular indented endings, 330‒600 µm long, with clone diameter 25‒40 µm. Trichotriaenes particularly small, with minute spines scattered in rhabds and deuteroclads, and blunt or conical endings: 31‒40 × 2.6‒4.7 µm overall length, some smooth trichotriaenes in the smallest size, diameter of cladome 26‒52 µm; no dichotriaenes found; oxeas 148‒153.4 µm. Two or three types of microscleres: amphiaster, and streptaster to spiraster 13‒31.2 µm.

Etymology. The name microtriaeneae refers to the tiny size of the trichotriaene spicule type. Apparently, there is not such a smaller size like this in other congener species.

Geographic distribution. Only known from the type locality.

Ecology. This is a stygobite species; observed from 4.5 to 7.6 m deep.

Remarks. Neosiphonia microtriaeneae clearly distinguishes for having minute triaenes, specifically from the trichotriaene type with microspined deuteroclads and rhabds; additionally, it lacks a pedunculated base or markedly reduced base of attachment; has smaller spicule sizes with various microsclere types, from amphiaster to espirasterlike.Altogether traits different from the four extant Neosiphonia species. N. superstes Sollas, 1888 from Fiji Islands, at 576‒ 430 m depth, has desmas reaching 500‒700 µm, a dichotriaene cladome 348‒550 µm, with rhabds 100‒200 µm, oxeas 675‒2280 µm, microscleres 32‒45 µm. N. fruticosa (Wilson, 1925) from the Philippines has desmas 160 µm, dichotriaene primary clads 30‒35 µm, secondary clads 100‒130 µm long, with rhabds 105‒125 µm long, oxeas 100‒240 some possibly foreign 400‒600 µm, microscleres 20‒24 µm. N. motukawanui Kelly, 2007 from New Zea- land, at 780‒910 m depth, has desmas 460‒800 µm long, dichotriaene cladomes 523‒619 µm with rhabds 100‒142 µm, oxeas 600 µm others broken, microscleres 18‒38 µm (Data according to Kelly, 2007). Neosiphonia schmidti Sollas, 1888 probably belongs to a different genus according to Pisera & Lévi 2002 on account of its desma different to the genus Neosiphonia , they also quote the presence of a fragment in Havana. Moreover, coordinates settled in Sollas’s habitat (22°9’30” N 52°21’20” W) clearly justifies not being in the Gulf of Mexico or Cuba.

We suggest extending the suite of diagnostic characters of the genus Neosiphonia with the new species presented, inserting: rounded body supported or not on a stem, smooth or spiny dichotriaenes, and microscleres amphiasters to spirasters.

Figures

FIGURE 10. Neosiphonia microtriaeneae sp. nov. a) Holotype CNPGG-1487 (ethanol); b) skeletal arrangement (transversal section, LM); c) ectosomal skeleton (tangential section, SEM).

FIGURE 11. Neosiphonia microtriaeneae sp. nov. Holotype CNPGG-1487 spicules; a-b) Tetraclone desmas, smooth clones with indented endings (LM, SEM); c) juvenile desmas (SEM); d-e) Oxeas hastate (LM, SEM); f) Trichotriaenes (SEM); g-i) Amphiasters to spherasters and spiraster types (LM, SEM).