Valiguna crispa Mitchueachart & Panha, 2024

Mitchueachart, Bowornluk, Sutcharit, Chirasak, Tongkerd, Piyoros & Panha, Somsak, 2024, Morphological and molecular evidence uncovers hidden species diversity in the leatherleaf slug genus Valiguna (Systellommatophora, Veronicellidae) from Thailand, ZooKeys 1212, pp. 79-107 : 79-107

Valiguna crispa Mitchueachart & Panha sp. nov.

Figs 2 , 3 D , 4 C , 7 C , 9

Type material.

Holotype • CUMZ 16094 (length 28 mm, width 10 mm; Figs 4 C , 9 A ) . Paratype • CUMZ 16097 (1 specimen in ethanol) .

Type locality.

Tham Kamin , Ban Na San, Surat Thani Province, Thailand, 8 ° 49 ' 49.4 " N, 99 ° 22 ' 44.2 " E.

Diagnosis.

Notum dark brown with random pale yellow and blackish spots, and median dorsal line visible. Hyponotum and foot paler in colour, and with scattered blackish spots. Penis cylindrical shaped and distally curved with wavy-like glans; vas deferens opens at peak. Penial tubules consist of 11 long tubules.

External characteristics.

Preserved specimen. Notum pale brown with scattered small pale yellow and blackish spots. Body elongated ovate, 21–28 mm (24.5 ± 3.5 mm) long and 8–10 mm (9.0 ± 1.0 mm) wide. Median dorsal line thin and narrow, and paler colour than notum. Hyponotum pale beige and with many tiny blackish spots. Foot beige, and narrower (width 2.0 mm, mean 2.0 ± 0.0 mm) than right hyponotum width. Male genital pore located close to base of right lower tentacle. Female genital pore located approximately midway of body on right hyponotum (Fig. 9 A ).

Live specimen. Notum dark brown with scattered tiny pale beige and blackish spots. Median dorsal line thin and indistinct colour. Hyponotum beige with scattered tiny blackish spots. Foot beige (Fig. 4 C ).

Genital organs. Penis acropleurocaulis type; penis base (pb) slightly concave, surrounding penis and relatively short. Penis glans (gn) elongated conical shaped, slightly tapering, and then bending to form pointed peak with wavy-like structure on penis glans surface. Vas deferens (vd) opens at tip of peak. Peak (pk) cylindrical shaped and located at lateral side of penis glans (Fig. 9 B ). Penial gland with conical papilla (pa). Penial tubules with 11 long tubules (lt) (Fig. 9 C ).

Bursa copulatrix duct (db) bottle shaped, slightly enlarged cylindrical near genital pore and tapering to short and narrow near bursa copulatrix; looks similar to a bottle with neck positioned off-centre to one side. Bursa copulatrix (bc) almost oval shaped and connected to bursa copulatrix duct. Oviduct (ov) and albumen gland (ag) enlarged, soft lobulated, and tufted; oviduct opened at female genital pore (fg). Distal (dd) and proximal (pd) posterior deferens inserted into somewhat oval-shaped prostate gland (pr). Middle deferens (md) penetrates into thick muscular right hyponotum then emerges near male genital pore (mg) before inserting into penis. Canalis junctor (cj) penetrates at nearly proximal of bursa copulatrix duct (near female genital pore). Fertilisation complex (fc) short and small tube; seminal vesicle (sv) thin and curly, and attached to albumen gland with thin connective tissue. Spermioduct (sd) thin, unconvoluted, and contracts into numerous globular hermaphroditic gland subunits. Hermaphroditic gland (hg) consists of many large subunits (Figs 3 D , 9 D ).

Radula. Teeth arranged in nearly straight rows, each row containing 57 teeth with half row formula 1–28. Central teeth very small and unicuspid. Lateral and marginal teeth not differentiated, monocuspid, large triangular shaped, and with slightly pointed cusp. From inner to outer, lateromarginal teeth gradually narrower, smaller, and rather pointed cusp, and outermost teeth relatively small (Fig. 7 C ).

Etymology.

The specific name crispa is from the Latin word crispus meaning wavy or curly, which refers to the structure found on the penis surface of this species.

Distribution.

Valiguna crispa sp. nov. is known only from the type locality, a limestone outcrop with low vegetation in southern Thailand (Fig. 1 ).

Comparative diagnosis.

Valiguna crispa sp. nov. differs from V. siamensis by having a wavy-like structure on penis glans, and with 11 tubules of equal length without any bifurcation, whereas V. siamensis possesses a cylindrical-shaped honeycomb structure at the tip of penis glans, along with 21–31 penial tubules of varying lengths (two short and 19–29 long), and two bifurcation penial tubules (Table 4 ).

This new species can also be distinguished from V. flava by having wavy structure on penis glans, and with 11 tubules of equal length without any bifurcation. In comparison, V. flava presents a surrounding structure at base of penis glans, resembling annular ring, and glans has dentate and serrate formations that envelop the dorsal side of the glans curvature. Additionally, V. flava possesses approximately 15 short penial tubules (Table 4 ; Gomes et al. 2008).

Remarks.

Generally, V. crispa sp. nov. has an external morphology very similar to the other congeners, except that this new species tended to have a weaker or indistinct median dorsal line.

Figures

Figure 1. Geographic distribution of Valiguna siamensis, V. semicerina sp. nov., and V. crispa sp. nov. based on the specimens examined herein.

Figure 2. Phylogenetic tree showing the relationships among species of Valiguna based on the COI gene sequences. Numbers by the nodes are the ML BS (left) and BI PP (right) values. Note, SH-aLRT ≥ 80 %, aBayes ≥ 0.95, BS ≥ 95 %, and PP ≥ 0.95 for each node were determined to be well supported. (*) indicates the holotype and (**) indicates the topotype.

Figure 3. A schematic drawing showing an arrangement of the reproductive system of Valiguna B – D female reproductive system of B V. siamensis, specimen CUMZ 16054 from Chanthaburi C V. semicerina sp. nov., holotype CUMZ 16087 from type locality, and D V. crispa sp. nov., holotype CUMZ 16094 from type locality.

Figure 4. Living slugs A Valiguna siamensis, specimen CUMZ 16038 from Khon Kaen (length ~ 60 mm) B V. semicerina sp. nov., holotype CUMZ 16087 from type locality (length ~ 34 mm), and C V. crispa sp. nov., holotype CUMZ 16094 from type locality (length ~ 28 mm). Dorsal view (left) and ventral view (right).

Figure 7. SEM images of radula A Valiguna siamensis, specimen CUMZ 16054 from Chanthaburi B V. semicerina sp. nov., holotype CUMZ 16087 from type locality, and C V. crispa sp. nov., holotype CUMZ 16094 from type locality. Central tooth indicated by ‘ C’.

Figure 9. Valiguna crispa sp. nov., holotype CUMZ 16094 from type locality A dorsal and ventral views B penis C penial gland and penial tubules, and D dorsal and ventral view of female genitalia.