Amphoriscus decennis, Chagas & Cavalcanti, 2021

Chagas, Cléslei & Cavalcanti, Fernanda F., 2021, Partial taxonomic revision of Amphoriscus Haeckel, 1870 (Porifera: Calcarea) with description of A. decennis sp. nov., Zootaxa 5061 (1), pp. 39-68 : 57-58

Amphoriscus decennis sp. nov.

Etymology: From the Latin decem + annus (meaning decades). The name is related to the time span the specimens remained in the collection before being recognised as a new species.

Diagnosis: Amphoriscus with cortical skeleton comprised of trichoxeas and one type of tetractine variable in size, subatrial skeleton comprised of triactines and atrial tetractines.

Type material: UFRJPOR 9031 holotype ( Île Riou , Marseille, France; 05/VI/1967) . UFRJPOR 9032, UFRJPOR 9033, UFRJPOR 9034, and UFRJPOR 9035— paratypes ( Île Riou , Marseille, France; 05/VI/1967) .

Type locality: Île Riou , Marseille, France .

Additional material: UFRJPOR 5822 ( Île Riou , Marseille, France; 05/VI/1967). Several fragments from one or more specimens. BMNH 1955.12 .13.9 (Plymouth; R. W. H. Row) .

Morphology: The specimens are cylindrical, with differences in thickness along the body, as they are thicker at the base. Smooth surface, colour white in spirit. The osculum is apical and naked. The holotype (UFRJPOR 9031) measures 2.0 x 1.0 cm (height x width), while the largest specimen, the paratype UFRJPOR 9035, measures 3.0 x 1.0 cm ( Fig. 10A ). The atrial cavity occupies the entire body of the specimen. The aquiferous system is syconoid and seems slightly disorganised in the paratype UFRJPOR 9032, possibly due to the presence of embryos and amphiblastulae.

Anatomy: The organisation is typical of Amphoriscidae , with an inarticulate skeleton formed mainly by giant cortical tetractines ( Fig. 10B ). Smaller tetractines also occur in the cortex and are less abundant than the giant ones. Trichoxeas are present ( Fig. 10C ). The inarticulation of the skeleton is due to the apical actine of the cortical tetractines and the unpaired actines of subatrial triactines ( Fig. 10D ). The atrial region is comprised exclusively of tetractines with short apical actines ( Fig. 10E, F ). These short apical actines and those of the giant cortical tetractines perforate the atrial cavity, making the atrial surface hispid.

Spicules ( Table 7; Fig. 11 ):

Cortical tetractines: Actines are conical and blunt. The paired actines are curved, while the unpaired one is straight. Apical actine is long, straight, and usually extends up to the atrial cavity ( Figs. 11A , A’).

Subatrial triactines: Actines are cylindrical to slightly conical, with blunt tips. The paired actines are curved from the base to the tips and are always smaller than the unpaired one ( Fig. 11B ).

Atrial tetractines: Actines are cylindrical and sharp. The paired actines are long and curved from the base to the tips. Unpaired actine is curved and usually smaller than the paired actines. The apical actine is short and straight or slightly curved ( Figs. 11C , C’).

Remarks: Amphoriscus decennis sp. nov. does not present anchoring spicules or peduncle, which differs from A. ancora , A. chrysalis , A. cyathiscus , A. pedunculatus , A. synapta , and A. testiparus . Among the remaining species, A. semoni most closely resembles the new species due to its skeletal organisation: cortical tetractines, subatrial triactines, and atrial tetractines. Nevertheless, the atrial tetractines of A. decennis sp. nov. have smaller apical actines [holotype: 47.0– 61.2 ±9.3–73.4/ 9.4– 10.7 ±1.1–13.2 μm] than the type of A. semoni [according to the original description, the apical actine is 100–130/ 9 μm; Breitfuss (1896)]. Among the proposed paratypes, the largest apical actine of the new species was 97.2 μm (maximum value, obtained for the specimen UFRJPOR 9033). Although close to the minimum value of the size range described by Breitfuss (1896), the measurements found here for A. decennis sp. nov. for this actine are, in general, smaller than in A. semoni . Additionally, cortical spicules are considerably thicker in A. decennis sp. nov. (holotype —paired: 31.9–58.5 μm, unpaired 30.1–41.4 μm, apical 35.0–52.1 μm versus paired: 10–20 μm, unpaired 10–20 μm, apical 19–27 μm in A. semoni ). Finally, only A. decennis sp. nov. has trichoxeas. The presence of small cortical tetractines in A. decennis sp. nov. may also be useful to differentiate it from A. semoni , although we considered them to belong to the same category as the giant cortical tetractines.

The geographical distribution of both species is also different. Type specimens of A. decennis sp. nov. were sampled in the Mediterranean Sea (more specifically at Île Riou, Marseille, France), while A. semoni is known to occur across the central Indo-Pacific region (type locality— Ambon Island, Indonesia). A specimen of A. decennis sp. nov. from Plymouth was also recognised (as discussed along with the remarks of A. chrysalis ), which remains consistent with a separate species distribution from that of A. semoni . A wide distributional range is not common in calcareous sponges and has been associated with erroneous taxonomic identification [such as the specimen BMNH 1886.6.7.32, from Australia, previously identified as A. cylindrus by Burton (1963)] or with the occurrence of introduced species. Since there is no reason to suspect that A. semoni could have invaded regions outside the Indo-Pacific, we consider the distribution additional evidence to support the new species.

Distribution: Mediterranean Sea and Plymouth, United Kingdom (BMNH 1955.12.13.9; see remarks of A. chrysalis ). Corresponding MEOW: Western Mediterranean and Celtic Seas ( Spalding et al. 2007).

Figures

FIGURE 10. Amphoriscus decennis sp. nov. (holotype UFRJPOR 9031). A—Specimen preserved in ethanol (UFRJPOR 9035). B—Transversal section showing a general view of the skeleton. C—Trichoxea protruding from the cortex. D—Subatrial region consisting of triactines (arrow). E, F—Atrial region composed exclusively of tetractines. Abbreviations: at—atrium and ct—cortex.

FIGURE 11. Amphoriscus decennis sp. nov. (holotype UFRJPOR 9031). A, A’—Cortical tetractines. B—Subatrial triactine. C, C’—Atrial tetractines.

Tables

TABLE 7. Spicule measurements of Amphoriscus decennis sp. nov. (H)—holotype; (P)—paratype; p—paired; u— unpaired; a—apical.

Specimen/ Spicules	Actines	Length (μm)				Width (μm)				N
		Min.	Mean	SD	Max	Min.	Mean	SD	Max
UFRJPOR 9031(H)
Cortical tetractines	p	289.1	409.9	61.6	529.5	31.9	42.2	6.2	58.5	30
	u	255.0	231.8	203.4	381.9	30.1	26.5	2.9	41.4	20
	a	296.5	450.0	78.4	635.3	35.0	43.1	5.0	52.1	30
Subatrial triactines	p	130.4	193.9	31.1	257.5	10.1	15.2	2.9	22.6	30
	u	208.7	362.8	59.0	476.1	11.2	17.1	3.3	25.5	30
Atrial tetractines	p	135.3	211.6	43.9	332.8	10.2	14.3	1.8	18.2	30
	u	139.7	198.8	35.6	249.6	11.2	14.5	1.5	19.1	10
	a	47.0	61.2	9.3	73.4	9.4	10.7	1.1	13.2	30
UFRJPOR 9032 (P)
Cortical tetractines	p	246.3	358.4	58.8	478.8	26.3	34.0	4.5	46.0	30
	u	299.0	230.7	134.6	414.7	33.0	29.7	10.5	44.9	19
	a	333.9	490.9	81.7	626.3	24.1	32.8	4.0	40.0	30
Subatrial triactines	p	107.2	156.6	31.3	208.0	5.8	12.1	2.4	16.1	30
	u	156.5	361.8	102.5	563.0	8.8	13.5	3.0	18.6	30
Atrial tetractines	p	149.6	210.7	37.3	309.4	7.2	12.3	2.3	15.8	30
	u	146.4	197.1	38.7	298.6	8.9	13.2	1.7	16.6	30
	a	48.1	65.7	10.2	81.8	8.7	11.0	1.5	13.1	30
UFRJPOR 9033 (P)
Cortical tetractines	p	221.9	338.4	55.7	453.5	18.5	25.7	4.6	39.3	30
	u	239.0	284.7	32.0	316.6	15.8	22.7	4.9	29.9	10
	a	140.6	398.0	163.6	648.2	21.8	26.9	4.0	38.5	30
Subatrial triactines	p	103.1	164.0	36.9	214.	7.6	11.5	2.1	17.2	30
	u	233.6	347.5	57.3	448.0	7.5	12.0	2.0	15.8	30
Atrial tetractines	p	140.6	191.3	32.3	279.6	6.1	11.4	3.5	23.9	30
	u	120.6	228.8	55.2	374.0	7.5	12.1	3.1	22.7	30
	a	49.7	75.0	33.3	97.2	5.3	8.6	3.8	10.5	23