Boucheona corbierensis Marchán & Decaëns, 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 : 73-75

Boucheona corbierensis Marchán & Decaëns sp. nov.

urn:lsid:zoobank.org:act: B39B20F1-1882-4A89-88C5-00FCABA96CC4

Hormogaster praetiosa Michaelsen, 1899 in Bouché (1972) (partial)

Etymology

The species name is derived from the natural region of Corbières where the type specimens were collected.

Material examined

Holotype

FRANCE • Adult; Occitanie , Aude , Portel-des-Corbières 19/03/2021; leg. D. F. Marchán, T. Decaëns, Y. Capowiez; Locality PCORB: 43.039109 2.949103; cleared meadow between pine forest and orchard; BOLD Sample ID: DFM-0030 ; deposited in MNHN.

Paratypes

FRANCE • 2 specimens, one adult and one subadult; same data as holotype: BOLD Sample ID: DFM-0029 and DFM-0031 ; deposited in MNHN. 4 specimens, adults; Occitanie , Pyrénées Orientales , Rivesaltes 15/04/2012; leg. D. F. Marchán, R. Fernández; Locality RIV: 42.757328 2.886342; garrigue; voucher: UCMLT00395 , UCMLT00396 , UCMLT00397 , UCMLT00398 ; deposited in UCMLT. 1 specimen, adult; Occitanie , Aude , Bizanet , Quillanet 18/11/2021; leg. D. F. Marchán; Locality #536: 43.146, 2.894; abandoned culture; BOLD Sample ID: DFM-0968 ; deposited in ECOSOLS. 3 specimens, adults; Occitanie , Aude , Durban-Corbières 18/11/2021; leg. D. F. Marchán; Locality #1072: 42.993, 2.792; grassland; BOLD Sample ID: DFM-0972 , DFM-0973 , DFM-0974 ; deposited in ECOSOLS.

Diagnosis

Pigmentation brownish-grey to dark brown, average length (fixed) of 21.8 cm (17.5–24 cm), average weight of 15.1 gr (13.5–16.7 gr), average number of segments of 437 (376–501). Clitellum extending over segments (XIII)XIV-XXIX(XXX), tubercula pubertatis as a continuous line on segments XXII-XXIX, multichamber discshaped spermathecae in intersegments 9/10 and 10/11, typhlosole composed of a maximum of 15 lamellae, first nephridial cecae in XI.

Morphological description

External morphology. All quantitative characters were measured in mature, whole individuals. Average length (fixed): 21.8 cm (17.5–24 cm). Average weight: 15.1 gr (13.5–16.7 gr). Average number of segments: 437 (376–501). Pigmentation: Brownish grey to dark brown on living specimens, with pigmentation neatly interrupted at the level of chaetae b ( Figure 4a ). Clitellum may be darker brown or lighter grey in colour, depending on the stage of development. Dorsally grey, ventrally beige on fixed specimens. Prostomium prolobic, strongly developed and with a small invagination delimiting a small prostomium-like lobe ( Fig 4b ); longitudinal striation on segments I, II and III. Strongly developed cephalic keels on segments I to XXIII ( Fig. 4b, 4c ). Closely paired chaetae; interchaetal ratio at segment XXXX, aa: 78, ab: 1, bc: 9, cd: 1, dd: 71. Nephridial pores in a row between chaetae b and c (very close to b). Spermathecal pores at intersegments 9/10 and 10/11 at the level of cd. Male pores open over chaetae ab at intersegment 15/16, surrounded by heart-shaped porophores. Female pores in segment XIV at the same level as male pores. Clitellum ring shaped- (only when wholly developed) extending over segments (XIII)XIV-XXIX(XXX) ( Figure 4c ). Tubercula pubertatis as a continuous line on segments XXII-XXIX. Papillae of chaetae ab in variable positions between segments XI, XII, XIII, XIV, XVII-XXII.

Internal anatomy. Funnel-shaped, strongly thickened septa in 7/8 to 11/12. Clearly developed hearts in 6–11. 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. Gut content frequently includes vegetal fibers. Typhlosole begins around segments XX with 13 lamellae, increasing to 15 lamellae in some individuals. 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 on the usual elongated shape.

Fraying testes and iridescent seminal funnels in segments 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 larger. Genital chaetae lanceolate with strong dorso-ventral differentiation and ornamented tip ( Fig. 3a,b ). The general shape of the tip of the chaetae is that of a broad dorso-ventrally flattened rhombus. A long portion of the distal part of the tip has a smooth surface, while the rest is ornamented by the usual hairy grooves. A moderate, longitudinal dorso-ventral depression can be observed in some of the chaetae. Average diameter: 34 (widest part)-24 μm. Average length: 1150 μm.

Remarks

Boucheona corbierensis sp. nov. resembles B. catalaunensis , B. gallica , Boucheona tenebrae sp. nov. and B. rosae in the position of the clitellum (XIV-XXIX, XXX), type and position of spermathecae (multichamber discshaped spermathecae in intersegments 9/10 and 10/11) and pigmentation (dorsal, dark brown-grey). They differ from all of these close relatives in the position of the tubercula pubertatis (XXII-XXIX), from Boucheona tenebrae sp. nov. in its smaller size and lighter pigmentation, and from B. catalaunensis and B. gallica in the position of the first nephridial caecae (XI vs XII) and in the maximum number of typhlosole lamellae (15 vs 13).

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

Distribution and ecology

B. corbierensis sp. nov. is known from two localities of Aude and Pyrénées Orientales and is probably present in another 3 localities (from Bouché (1972) putatively assigned by geographic proximity) in an area of 1,200 km 2 ( Figure 5 ). It inhabits sclerophyllous woods and shrublands, sometimes occupying edges of neighbouring orchards.

Laboratory experiments (Capowiez in prep.) have shown that B. corbierensis sp. nov. behaves like an anecic earthworm, which is consistent with its pigmentation, morphology and gut content (vegetal fibers).

Figures

FIGURE 3. Scanning electron micrographs of genital chaetae of four populations of French Boucheona. Scale bar: 10 µm.

FIGURE 4. External morphology of Boucheona corbierensis sp nov. a) Live specimen. b) Detail of the cephalic region, fixed specimen. c) Cephalic and clitellar region of a fixed specimen. cl: clitellum; tp: tubercula pubertatis; gp: genital papillae. Scale bar: 3 centimeters.

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.