Boucheona tenebrae Marchán & Novo, 2023

Marchán, Daniel F., Novo, Marta, Domínguez, Jorge, Sánchez, Nuria & Decaëns, Thibaud, 2023, Contribution to the knowledge of the genus Boucheona (Oligochaeta Hormogastridae) in France with a newly described species and a redescribed species, Zootaxa 5255 (1), pp. 68-81 : 75-78

Boucheona tenebrae Marchán & Novo sp. nov.

urn:lsid:zoobank.org:pub:FA29B304-DD7C-4472-BDE2-618B80557709

Hormogaster praetiosa var. nigra Bouché, 1970

Etymology

This species name refers to its very dark, almost black pigmentation.

Material examined

Holotype

FRANCE • Adult; Occitanie , Aude , Quillan 19/04/2008; leg. M. Novo, R. Fernández; Locality 1 (QUILL):

42.880222 2.170000; shrubland on a pronounced slope; voucher UCMLT00393 ; deposited in the UCMLT.

Paratypes

FRANCE • 1 specimen, adult; 16/04/2012; leg. D. F. Marchán, R. Fernández, same data as holotype; voucher UCMLT00394 ; deposited in UCMLT.

Diagnosis

Pigmentation almost black with purple iridescence, length reaching 50 cm, weight reaching 27.36 gr, number of segments reaching 600. Clitellum extending over segments XIV-XXX, tubercula pubertatis as a continuous line which narrows towards the end on segments XXII-XXVII(XXVIII), first thickened septum in 6/7, multichamber disc-shaped spermathecae in intersegments 9/10 and 10/11, typhlosole composed of a maximum of 13 lamellae, first nephridial cecae in XI.

Morphological description

External morphology. Recently collected specimens (used for molecular information) are incomplete and damaged, thus some characters refer to the description of Hormogaster praetiosa var. nigra (Bouché, 1970)

Length: 50 cm according to Bouché 1970 (living specimens?). Weight (holotype): 27.36 gr (20-25 according to Bouché 1970). Number of segments (holotype): 580 (more than 600 according to Bouché 1970). Pigmentation: Almost black with purple iridescence on living specimens, with pigmentation neatly interrupted at the level of chaetae b. Dorsally dark grey, ventrally beige on fixed specimens. Prostomium prolobic, strongly developed and with a small invagination delimiting a small prostomium-like lobe; longitudinal striation on segments I, II and III. Strongly developed cephalic keels on segments I to XIII. Closely paired chaetae; interchaetal ratio at segment 40, aa: 50, ab: 1, bc: 8, cd: 1, dd: 50. Nephridial pores in a row between chaetae b and c (very close to b). Spermathecal pores on intersegments 9/10 and 10/11 at the level of cd. Male pores open over chaetae ab at the intersegment 15/16, surrounded by heart-shaped porophores. Female pores in segment XIV at the same level as male pores. Clitellum ring shaped-shaped (only when wholly developed) extending over segments XIV-XXX. Tubercula pubertatis on XXII-XXVII(XXVIII) as a continuous line which narrows towards the end. Papillae of chaetae ab in variable positions between segments XIII, XIV, XVII-XXIII, XXVIII, XXIX.

Internal anatomy. Funnel-shaped, strongly thickened septa in 7/8 to 11/12, moderately thickened in 6/7. Clearly developed hearts in VI-XI.Three shiny, strongly muscular gizzards in VI, VII and VIII. Morren's glands and intestinal gizzard not apparent. First section of the intestine slightly dilated. Typhlosole begins around segments XX with 9 lamellae, which swiftly increase to a maximum 13 lamellae and the decrease to 11 lamellae. Anterior nephridial bladders U-shaped with very close branches and no apparent caecum until segment XI. Bladders gradually flatten towards the end of the body, taking the usual elongated shape.

Fraying testes and iridescent seminal funnels in X and XI. Two pairs of voluminous, grainy seminal vesicles in XI and XII. Ovaries and female funnels in XIII, ovisacs in XIV. Two pairs of multichamber disc-shaped spermathecae in intersegments 9/10 and 10/11, the posterior pair bigger.

Remarks

Boucheona tenebrae sp. nov. resembles B. catalaunensis , B. gallica , B. corbierensis sp. nov. and B. rosae in the position of the clitellum (XIV-XXIX,XXX) and type and position of spermathecae (multichamber disc-shaped spermathecae in intersegments 9/10 and 10/11). It differs from these close relatives in its larger size (length, weight, number of segments), its darker pigmentation (almost black vs brown-dark brown) and the position of the first thickened septum (6/7 vs 7/8). In addition, it differs from B. corbierensis sp. nov. in the position of the tubercula pubertatis (XXII-XXVII(XXVIII) vs XXII-XXIX) and maximum number of typhlosole lamellae (13 vs 15).

COI uncorrected average pairwise distances and topology of multilocus molecular phylogenetic trees support the status of B. tenebrae sp. nov. as independent from other morphologically similar species.

Distribution and ecology

B. tenebrae sp. nov. is known from a single locality of Aude ( Figure 5 ). It inhabits shrublands.

Figures

FIGURE 5. Known localities of Boucheona corbierensis sp nov., Boucheona tenebrae sp nov. and their closest relatives. White dots indicate previously sampled and analyzed populations. Black dots indicate populations sampled and analyzed during this work. White squares indicate localities from Bouché (1972), which were putatively assigned to the different species due to geographic proximity.