Meretrix taiwanica (Bivalvia: Veneridae), a previously misidentified new species in Taiwan

Figures & data

Figure 1. The type locality of Meretrix taiwanica sp. n. in the Tamsui River estuary, northern Taiwan.

Figure 2. A, Environment of type locality; B, local fisherman catches Asian hard clams in single small boat; C, use of a bull raker as harvesting gear; D, harvested wild Asian hard clams.

Figure 3. Morphometric measurements of right valve and shell. L: shell length, H: shell height, B: shell breadth, AL: anterior shell length, SW: socket width, SL: socket length, UH: upper shell height, LPM: length of posterior dorsal margin, HPM: height of posterior dorsal margin, LL: ligament length, and PL: pallial sinus length.

Table 1. Table of species, sample collecting localities and GenBank accession numbers that were used in this study.

Species	Collecting locality	GenBank no.
Meretrix taiwanica sp. n.	Taiwan	MN275933–MN275941 MZ453092–MZ453103 (this study) Holotype, MT622847 (this study) Paratype, MT622848, MT622849 (this study)
Meretrix lusoria	China Japan South Korea	JN898935, GQ903339, JQ294065, JN043624 KX534323, AB280786, AB853864, MT418596 AB853870
Meretrix lamarckii	China Japan	JN043625, KY318175 AB059420, KP244452
Meretrix lyrata	Philippines China	KF009624 HQ703198, JN898944, KC832317
Meretrix meretrix	China	DQ399402 (M. petechialis), KP976274 (M. petechialis), MF038859 (M. petechialis), GQ463598 (M. petechialis), JN898949 (M. petechialis)
Meretrix petechialis	China South Korea Japan (from market)	EU145977, KY318078, KX534315 JX503043 MN308465-MN308468

Figure 4. A, Holotype, FRIM10028, paired valves; B, inner shell of right valve of holotype, aa: anterior adductor scar, pl: pallial line, ps: pallial sinus, pa: posterior adductor scar; C, paratype, FRIM10029; D, paratype, FRIM10030.

Figure 5. Colour patterns of Meretrix taiwanica sp. n., FRIM10031.

Table 2. Measurements (in mm) of type specimens of Meretrix taiwanica sp. n.

L: shell length; H: shell height; AL: anterior shell length; SW: socket width; SL: socket length; UH: upper shell height; LPM: length of posterior dorsal margin; HPM: height of posterior dorsal margin; B: shell breadth; LL: ligament length; PL: pallial sinus length.

ID	L	H	AL	SW	SL	UH	LPM	HPM	B	LL	PL
Holotype (FRIM10028)	67.9	57.2	14.7	4.1	16.3	22.6	49.0	8.3	32.6	11.9	15.6
Paratype (FRIM10029)	56.5	45.2	10.6	4.3	21.8	20.3	40.6	7.3	30.3	10.1	12.8
Paratype (FRIM10030)	49.4	37.8	11.6	4.9	13.4	19.2	36.3	5.8	29.5	9.6	11.5

Figure 6. Shells of hard clams A, Meretrix taiwanica sp. n.; B, M. petechialis; C, M. lusoria; D, Cytheraea formosa (unavailable name-bearing types, syntype, digital image cited from BMNH HP collection, 20120227).

Table 3. Ten characters standardised against shell length calculated in M. taiwanica sp. n. (N = 70), M. petechialis (N = 17), M. lusoria (N = 24) and C. formosa (N = 2) (unavailable name-bearing types). Avg.: mean, Std.: standard deviation, L: shell length, H: shell height, B: shell breadth, AL: anterior shell length, SW: socket width, SL: socket length, UH: upper shell height, LPM: length of posterior dorsal margin, HPM: height of posterior dorsal margin, LL: ligament length, and PL: pallial sinus length.

Species	H/L	AL/L	SW/L	SL/L	UH/L	LPM/L	HPM/L	B/L	LL/L	PL/L
M. taiwanica sp. n.
Avg.	0.797	0.375	0.087	0.291	0.393	0.730	0.104	0.524	0.223	0.368
Std.	0.028	0.035	0.006	0.043	0.022	0.082	0.014	0.020	0.026	0.040
M. petechialis
Avg.	0.789	0.381	0.091	0.267	0.410	0.742	0.128	0.497	0.220	0.317
Std.	0.022	0.019	0.005	0.042	0.020	0.023	0.012	0.015	0.018	0.025
M. lusoria
Avg.	0.806	0.374	0.080	0.291	0.423	0.754	0.117	0.518	0.202	0.339
Std.	0.018	0.023	0.005	0.029	0.012	0.018	0.009	0.059	0.040	0.016
C. formosa *
Avg.	0.740	0.322	0.063	0.172	0.363	0.772	0.091	/	0.170	0.308
Std.	0.007	0.007	0.014	0.010	0.010	0.004	0.011	/	0.049	0.034

*C. formosa was measured using digital images, not actual samples; B/L value was not available.

Figure 7. Two-dimensional scatterplots of canonical discriminant analysis. A, Analysis including the species Meretrix taiwanica sp. n., M. petechialis, M. lusoria and C. formosa; B, analysis including the species Meretrix taiwanica sp. n., M. petechialis and M. lusoria.

Table 4. Centroids of canonical variates (Can.) 1 and 2 for 10 standardised characters of Meretrix taiwanica sp. n., M. petechialis, and M. lusoria. L: shell length, H: shell height, B: shell breadth, AL: anterior shell length, SW: socket width, SL: socket length, UH: upper shell height, LPM: length of posterior dorsal margin, HPM: height of posterior dorsal margin, LL: ligament length, and PL: pallial sinus length.

	H/L	AL/L	SW/L	SL/L	UH/L	LPM/L	HPM/L	B/L	LL/L	PL/L
Can. 1	0.205	0.162	−1.044	−0.569	2.632	0.732	2.634	0.113	−1.220	−2.322
Can. 2	1.251	−0.409	−2.866	1.144	0.877	0.266	−1.583	0.139	−1.038	1.278

Figure 8. Phylogenetic tree constructed for Meretrix spp. and reference sequences based on the cytochrome c oxidase I gene barcode sequence. Branch support values estimated by bootstrap pseudo-replicates in maximum parsimony and neighbour-joining are displayed above each branch. A minus sign (-) indicates that the bootstrap values were <75%.