Plectostoma H. Adams 1865

Figures 17.Photographs of 17 living Plectostoma species. A Plectostoma salpidomon (van Benthem Jutting, 1952), BOR 5569 B Plectostoma umbilicatum (van Benthem Jutting, 1952), BOR 5503 C Plectostoma palinhelix (van Benthem Jutting, 1952), BOR 5520 D Plectostoma kakiense (Tomlin, 1948), BOR 5516 E Plectostoma mengaburensis sp. n., BOR 5574 F Plectostoma kubuensis sp. n., BOR 5518 G Plectostoma whitteni sp. n., BOR 5536 H Plectostoma senex (van Benthem Jutting, 1952), BOR 5631 I Plectostoma crassipupa (van Benthem Jutting, 1952), BOR 5515 J Plectostoma ikanensis sp. n. Form BOR 5507, BOR 5507 K Plectostoma ikanensis sp. n. Form BOR 5504, BOR 5504 L Plectostoma sinyumensis (Maassen, 2001), BOR 5537 M Plectostoma crassipupa (van Benthem Jutting, 1952), BOR 5512 N Plectostoma siphonostomum (van Benthem Jutting, 1952), BOR 5557 O Plectostoma laidlawi (Sykes, 1902) Form BOR 5510, BOR 5510 P Plectostoma relauensis sp. n., BOR 5511 Q Plectostoma christae (Maassen, 2001), BOR 5505 R Plectostoma retrovertens (Tomlin, 1938), BOR 5559 S Plectostoma tohchinyawi sp. n., BOR 5533.

Figures 10.Aperture and peristome forms. A outer and inner peristome B Simple aperture without outer peristome C aperture with double peristomes in which the outer peristome is prominent D aperture with double peristomes in which the outer peristome is equally prominent as the inner.

Figures 9.Positioning scheme for the description of aperture and peristomes. A anterior, posterior, right and left lateral sides of aperture and peristome are defined according to the orientation of the shell relative to the active animal B Three shell examples showing the defined positions of aperture and peristome. Red arrows point to the aperture area with the densest ribs.

Figures 12.Spiral lines on the shell surface are shown in, from top to bottom, 100 × magnification under the dissecting microscope, 500 × and 2000 × magnification under scanning electron microscope. A shell with both thick and thin spiral lines B shell with only thin spiral lines. Each corresponding image in A and B is at the same scale.

Figures 13.Radial ribs. A measurement of number of ribs per mm at the whorl above the constriction in left lateral view B rib intensity, from left to right: thick ribs, thin ribs, and abraded ribs C three different rib shapes, from left to right: single-humped, slightly curved and straight.

Figures 18.Distributional records of Plectostoma species. A–D distribution records for each of 31 Plectostoma species.

Figures 16.The phylogeny of Diplommatinidae genera with Cochlostoma septemspirale (Wagner, 1897) as outgroup. Bayesian inference 50% majority-rule consensus trees based on the concatenated dataset consisting of parts of 28S, 18S, COI, and 16S. Bayesian posterior probabilities, percent bootstrap support after 1000 maximum likelihood replicates, and percent bootstrap support after 1000 maximum parsimony replicates are shown for the major clades. Clade A consists of Plectostoma species, Clade B consists of Opisthostoma species. The shell forms are shown for representative taxa. Details of the taxa can be found in Table 1 (no. 1–28, 42, 48, 61, 69, 71, 73, and 78). Scale bar = 1 mm.

Figures 3.Apex forms in shell left lateral view. The degree of shell apex depression results from the growth regime of the teleoconch after the protoconch.

Figures 11.Shell measurements. A height and width of spire B number of whorls C spire last whorl length, tuba whorl length and umbilicus openness.

Figures 4.Two basic forms of apical spire whorls: A oblong conical B depressed conical.

Figures 5.Three basic forms of shell spire basal whorls in left lateral view. Panels from left to right of each of the shell forms: quantifications of the shell form in top view; example of the shell form with a low number of whorls in left lateral view; example of the shell form with a higher number of whorls in left lateral view. A conical B ovoid C ellipsoid.

Figures 2.Morphological terminology and shell measurements. A shell part terminology as used in the species descriptions is shown in an example shell B Two shell examples show the basal spire that consist of the last two whorls of the spire, and the apical spire that consist of the remaining spire whorls.

Figures 6.Different types of parietal constriction teeth before the operculum resting site, in bottom view. A two long lamellae run parallel to the whorl growing direction B two short ridges run parallel to the whorl growing direction, each knob-shaped at one end C a single ridge runs parallel to the whorl growing direction, knob-shaped at one end D no tooth.

Figures 7.Different types of basal constriction teeth in top view. A two teeth after operculum resting site: one ridge runs parallel to the whorl growing direction; the other ridge has a knob at one end and runs perpendicular to the whorl growing direction B no tooth.

Figures 8.Different tuba coiling regimes in bottom view. A tuba type 1–tuba coiling as regularly as the spire last whorl B tuba type 2–tuba gradually coiling downward and then in a different direction C tuba type 3–tuba bent abruptly. Arrows point to the constriction.

Description: English: The Opisthostoma concinnum complex consists of 16 populations. All are restricted to small limestone outcrops along the lower Kinabatangan River in Sabah, Malaysian Borneo. The populations have been identified with five- or six-letter codes: BATANG (O. concinnum at Batangan), BODTAI (O. concinnum at Bod Tai), GOMcon (O. concinnum at Gomantong), GOMmir (O. mirabile at Gomantong), KAMPUN (O. concinnum at Batu Kampung), KERUAK (O. concinnum at Keruak), MATERI (O. concinnum at Materis), MAWAS (O. concinnum at Mawas), PANGI (O. concinnum at Pangi), QUARRY (O. concinnum at Quarry), TABAco (O. concinnum at Tandu Batu), TABAsi (O. simplex at Tandu Batu), TOMBEE (O. concinnum at the east side of Tomanggong Besar), TOMBEW (O. fraternum at the west side of Tomangong Besar), TOM-2 (O. concinnum at Tomanggong 2), TOMKEC (O. concinnum at Tomanggong Kecil). All populations are allopatric, except those from Gomantong, Tandu Batu, and Tomanggong Besar. From: Schilthuizen, M. et al., 2006. MICROGEOGRAPHIC EVOLUTION OF SNAIL SHELL SHAPE AND PREDATOR BEHAVIOR. Evolution, 60(9), 2006, pp. 1851–1858. Date: 12 October 2005. Source: Own work. Author: Schilthuizen.

Description: English: A bunch of snails of the species Plectostoma obliquedentatum, photographed on limestone rocks near Kampung Labang, Interior Province, Sabah. Date: 24 June 2005, 15:15:03. Source: Own work. Author: Schilthuizen.

Description: English: A portion of a representative collection of same-size microsnails from a Bornean limestone hill, showing the numbers achieved for evaluating the species-abundance distribution. (From: Schilthuizen, M., 2011. Community ecology of tropical forest snails: 30 years after Solem. Contributions to Zoology, 80 (1): 1-15.). Date: 28 October 2010. Source: Own work. Author: Schilthuizen.

front view. Catalog no.: 5595. Specimen ID: 2951778. Taxon rep.: Plectostoma anisopterum. Image quality: 4. Aspect ratio: 1.333.

front view. Catalog no.: 5586. Specimen ID: 2951780. Taxon rep.: Plectostoma wallacei. Image quality: 4. Aspect ratio: 1.333.

front view. Catalog no.: 5533. Specimen ID: 2951793. Taxon rep.: Plectostoma tohchinyawi. Image quality: 3. Aspect ratio: 1.333.

front view. Catalog no.: 5536. Specimen ID: 2951795. Taxon rep.: Plectostoma whitteni. Image quality: 3. Aspect ratio: 1.333.

front view. Catalog no.: 5537. Specimen ID: 2951797. Taxon rep.: Plectostoma sinyumensis. Image quality: 4. Aspect ratio: 1.333.

front view. Catalog no.: 5546. Specimen ID: 2951811. Taxon rep.: Plectostoma austeni. Image quality: 4. Aspect ratio: 1.333.