Diaphera prima, 2010

Sutcharit, Chirasak, Naggs, Fred, Wade, Christopher M., Fontanilla, Ian & Panha, Somsak, 2010, The new family Diapheridae, a new species of Diaphera Albers from Thailand, and the position of the Diapheridae within a molecular phylogeny of the Streptaxoidea (Pulmonata: Stylommatophora), Zoological Journal of the Linnean Society 160 (1), pp. 1-16 : 5-9

DIAPHERA PRIMA PANHA SP. NOV. ( FIGS 1B–G , 2 )

Type material: Holotype CUMZ 3544 (height 6.2 mm, width 2 mm, whorls eight) ( Fig. 1B, C ); paratypes CUMZ 3543 (2a shells), 3545 (3a ethanol; Fig. 1G ), 3627 (8a + 8j shells), 3629 (13a ethanol; Fig. 1E, F ), 3630 (1j shell; Fig. 1D ), 3649 (10a + 13j shells), 4299 (10a + 3j ethanol), 4656 (5a shells); BMNH 20070007 (2a shells); MNHN 21991 (2a shells); SMF 333515 (2a shells); ZMA 409052 (2a shells). Type locality: Khao Cha Ang-Oan , Bor Thong, Chonburi, Thailand (13°11′5″N, 101°34′59″E) . Other material examined: Khao Chakan, Srakeo, Thailand (13°39′80.2″N, 102°05′71.1″E): CUMZ 3541, 3542, 3546, 3628, 3650, 4296, 4297, 4298. Tam Khao Loy , Khao Chamao , Rayong, Thailand (13°03′28.9″N, 101°36′27.6″E): CUMZ 3800 .

Description: Shell small, turreted, tapering slightly away from apex, thin, transparent, and glossy when fresh; part of last whorl detached ( Fig. 1B ). Apex

,

†

smooth palatal Tenasserim

cylindrelloidea

and Obtuse ribbed

Closely Rounded Parietal,

thin,

Moulmein.

D

4.5 1.3 8 Burma 1

and smooth ribbed, palatal

, Burma

†

D.

seatoni

9.5 2.25 11 Obtuse Not closely

Ovate

, Parietal columellar Tenasserim 1.)

1908

, (Indochina from † brevicollis D. 8 2 11 and smooth Obtuse rib Distinct Rounded thin Parietal palatal, Tenasserim Moulmein, Burma 1 Godwin-Austen &, 1850 Blanford Albers

* and smooth rib

, palatal,

(

; 1899)

Diaphera . saurini

D 8.8 3 10 Obtuse Distinct Rounded Parietal, columellar Battambang Cambodia 2 Blanford

of); species short 1891 (five.. nov sp smooth only, suture below, palatals amongst

prima and smooth, 2 columellar, Thailand; Beddome 1871)

characters. D 6.2 2 7 – 8 Obtuse Almost ribbed Rounded Parietal basal Eastern 46 (Stoliczka shell in mm mm in. from of Comparison holotype of of holotype whorls aperture lamellae of examined 3.62.016 ZMA derived data of 2 Table. Characters height Shell Shell width Number Apex sculpture Shell of Shape Apertural Distribution number Total specimens * Holotype † Indicates smooth, obtusely conical. Whorls seven to eight (excluding detached section) slightly convex; suture depressed. Shell surface with very fine growth lines in appearance; short transverse ridges immediately below suture extend around circumference of detached section of body whorl. Detached part of last whorl long, being approximately one third the length of last whorl, descending, with sutural line extending as vallicular depression and corresponding with parietal lamella (P). Umbilicus wide, deep with strong transverse ribs. Aperture circular ( Fig. 1C ); inner surface with thin wrinkles. Lip slightly thickened and expanded. Dentition of peristome comprises one large and curved parietal lamella fold and two small palatal lamellae (Pl) (one on the margin of the peristome and one inside the peristome), one convex basal lamella (Bl), and one large internal columellar lamella (Cl) ( Fig. 1C ). Juvenile shell composed of about four whorls and shows distinct parietal, palatal, basal, and columellar lamellae in peristome ( Fig. 1D ).

Animal body colour externally pale greenish yellow; digestive gland pale brownish yellow, extended body entirely lacking bright skin pigmentation and bright red, orange, or yellow eye retractor muscles often associated with streptaxids ( Fig. 1E, F ). Foot narrow and undivided (holopoda), anterior long, posterior rather short as typical of streptaxids. Upper tentacle long with black eye spot on tip, lower tentacles very short.

Radula: Radula teeth arranged in anteriorly pointed V-shaped rows on the dorsal odontophore, each row contains 31–33 teeth with formula (15–16)–1–(15–16). Central tooth triangular, minute with pointed cusp. Lateral and marginal teeth weakly differentiated, unicuspid, lanceolate, basal plate well developed; lateral teeth gradually reduced in length and size towards radular margin; inner lateral teeth straight and slightly curved cusp ( Fig. 1G ).

Genitalia: Genital atrium (at) short. Penis (p) very long, slender with thick muscular wall. Epiphallus, penial verge and penial sheath absent. Vas deferens (vd) small tube, inserting on penial apex and almost coincident with attachment of penial retractor muscle. Penial retractor muscle (pr) thin, very long, originating from columellar muscle ( Fig. 2A ). Internal wall of penis smooth with two longitudinal pilasters (pp); major pilaster extends almost the entire penis length; minor pilaster about half as long. Penial armature in form of hooks characteristic of streptaxids entirely absent ( Fig. 2B ). Vagina (v) short, about one fifth of the length of the penis. Duct of gametolytic organ (gd) slender and short, ending without distinct gametolytic sac, and attached to free oviduct by thin connective tissue. Free oviduct (fo) long; oviduct (ov) enlarged with lobular shape (figured specimen contained one large spherical egg proximally). Inconspicuous prostate gland bound to external section of oviduct. Albumen gland (ag) thick, bean-shaped. Gonad (g) lobular; hermaphroditic duct (hd) slender and straight, bearing globular seminal vesicle (sv) in middle ( Fig. 2A ).

Distribution: The species is presently known from three localities, namely the isolated limestone hills at the type locality, at Khao Chakan, Srakeo, Thailand, and at Tam Khao Loy, Khao Chamao, Rayong, Thailand. The shells of specimens from Khao Chakan are slightly smaller than those from the type locality, but shell shape, sculpture, and apertural dentition are essentially identical to that of the type specimens. The slight difference in size is probably indicative of local population variation.

Etymology: From the Latin ‘ prima ’ meaning ‘first, original’. It refers to the fact that this new species is the first Diaphera definitely recorded from Thailand. Remark: Several of the Philippines Diaphera such as Diaphera canaliculata ( Quadras & Möllendorff, 1896) are pupiform with few whorls, and are quite distinct from the more common high, narrow shelled species ( Zilch, 1961). These two groups may represent distinct genera. We limit our discussion of Diaphera species to D. prima sp. nov. and the four high-spired geographically proximal (from Indochina) species, Diaphera cylindrelloidea ( Stoliczka, 1871) , D. seatoni ( Beddome, 1891) , Diaphera brevicollis ( Blanford, 1899) , and Diaphera saurini Benthem Jutting, 1962 .

Diaphera prima sp. nov. can be distinguished from these four regional species on the basis of several conchological characters (Table 2). Diaphera cylindrelloidea and D. brevicollis from Burma resemble each other in shell form with smooth embryonic whorls, distinct transverse ribs on the later whorls, and only parietal and thin palatal lamellae in the aperture ( Stoliczka, 1871; Beddome, 1891; Blanford, 1899; Blanford & Godwin-Austen, 1908). Compared to other species within the genus, D. seatoni from Mooleyit Mountain, Tenasserim, Burma, possesses a higher shell with distinct transverse ribs and the detached part of the last whorl is slightly shorter than D. prima sp. nov. ( Blanford, 1899; Blanford & Godwin-Austen, 1908). Diaphera seatoni can be distinguished from D. cylindrelloidea and D. brevicollis by its higher shell, ovate aperture with a sinus on upper corner, the presence of a basal lamella and shorter detached part to the last whorl ( Stoliczka, 1871; Beddome, 1891; Blanford & Godwin-Austen, 1908). In the morphologically similar species D. saurini from Cambodia ( Fig. 1H, I ), the fourth and later whorls have strong transverse ribs, the penultimate and last whorls are enlarged, and the basal lamella is absent ( Benthem Jutting, 1962).

The soft internal anatomy of a limited number of streptaxid genera has been previously described ( Table 3) and this is the first account of the reproductive anatomy of Diaphera . The anatomical descriptions of Sinoennea kanchingensis Tomlin, 1948 and Huttonella bicolor (Hutton, 1834) were the most comprehensive available for comparing the morphology of Diaphera ( Stoliczka, 1871; Berry, 1963, 1965; Schileyko, 2000). Diaphera possesses a very long penis, the penial retractor muscle inserts on the distal penis, being almost coincident with entry of the vas deferens; the gametolytic organ is slender, a short duct, and lacks a distinct gametolytic sac; the seminal vesicle is cylindrical. In Sinoennea and Huttonella Pfeiffer, 1856 the penis is shorter, the vas deferens inserts centrally on the penis, remote from the distally inserting penial retractor muscle; and the gametolytic organ has a long duct and terminates in a globular gametolytic sac.

Figures

Figure 1. A, shell morphology of Diaphera cumingiana (Pfeiffer, 1845) (lectotype BMNH 20080230). B–G, morphology of shell and radular and living animals of Diaphera prima sp. nov. B, the shell and C, the aperture of holotype (CUMZ 3544) showing lamellae. D, juvenile specimen showing apertural lamellae (paratype CUMZ 3630). E, F, living animals (paratype CUMZ 3629): E, shell height 6.5 mm; and F, shell height 6.8 mm. G, radula morphology (paratype CUMZ 3545); arrow on top-right inset indicates the central tooth. H, I, morphology of shell of Diaphera saurini Benthem Jutting, 1962. H, the shell and I, aperture of holotype (ZMA 3.62.016) showing lamellae. Abbreviations: P, parietal lamella; Pl, palatal lamella; Bl, basal lamella; Cl, columellar lamella.

Figure 2. Genitalia of Diaphera prima sp. nov. (paratype CUMZ 3545). A, whole genital system. B, details of internal wall of penis. Abbreviations: ag, albumin gland; at, atrium; eg, egg; fo, free oviduct; g, gonad; hd, hermaphroditic duct; ov, oviduct; p, penis; pp, penial pilasters; pr, penial retractor muscle; sv, seminal vesicle; v, vagina; vd, vas deferens.