Echinolittorina (Granulilittorina)

Key to species of Echinolittorina (Granulilittorina) in Indo-West Pacific

Owing to the high intraspecific variability of shells, to the few anatomical synapomorphies that define clades, and to the fact that the shape of the penis does not always discriminate between sister species, it is impossible to construct an entirely reliable key to these species. Any attempt must involve artificial groupings, subjective descriptions, and omission of extreme or rare shell variants. The following key has been based primarily on shell characters which, although so variable, are nevertheless the most accessible (and, with experience, among the most reliable) characters for identification. To these have been added two of the most useful and accessible anatomical characters, the penis and the coloration of the cephalic tentacles, both visible with only the minimum of dissection. The geographical distribution also provides important evidence for identification, since sister species and members of each of the seven phylogenetic groups are almost invariably allopatric. Identifications should be confirmed by reference to the detailed descriptions, figures and maps. Note that striae, ribs, and rows of granules or nodules, all run in a spiral direction around the shell, unless otherwise noted.

1 Smooth or with faint spiral grooves; tall-spired; small (<8 mm); black; Sunda Is ... E. sundaica View in CoL (Fig. 24)

- Variably striate, ribbed or granulose (e.g. Fig. 67) .................................................................................... 2

- Nodulose (e.g. Fig. 32) ............................................................................................................................ 10

2 Cephalic tentacles with basal transverse black band (Figs 41G, 63F) ....................................................... 3

- Cephalic tentacles with 1-3 longitudinal black lines ( Figs 5K, L View FIGURE 5 , 25A, 28D, E) ...................................... 8

3 Penial glandular disc small or absent (Figs 63A, 73A) ............................................................................. 4

- Penial glandular disc normal (Figs 28A, 51B) .......................................................................................... 5

4 Smooth to minutely granulose; white; Sri Lanka............................................. E. novaezelandiae View in CoL (Fig. 63)

- Finely granulose; brown mottled or reticulate pattern; central Indo-West Pacific (IWP) E. vidua View in CoL (Fig. 59)

- 2–5 strongly granulose carinate ribs; white or with zigzag axial black stripes; Pacific islands ................... ....................................................................................................................................... E. cinerea View in CoL (Fig. 64)

- Striate to granulose; white with large irregular black marks; Hawaiian Is ............ E. hawaiiensis View in CoL (Fig. 67)

- Axial rows of granules; white, or with axial brown lines; Indian and Pacific Oceans ................................. ................................................................................................................................... E. reticulata View in CoL (Fig. 69)

- Granules not in axial rows; white; Red Sea and Arabia ......................................... E. millegrana View in CoL (Fig. 72)

5 Grey with black and white dashes on 2–7 ribs .......................................................................................... 6 - White, or white finely mottled or lined with grey ..................................................................................... 7

6 Surface shiny; 3–7 main ribs; India and Sri Lanka.................................................. E. leucosticta View in CoL (Fig. 40)

- Surface dull; 2–4 main ribs, sometimes with small nodules; Java and Sumatra ..... E. biangulata View in CoL (Fig. 44)

- Surface dull; 2–3 main ribs with granules and small sharp nodules; western Pacific islands ...................... ..................................................................................................................................... E. tricincta View in CoL (Fig. 49)

7 Minutely to finely granulose; white with grey herringbone pattern, axial lines or mottling; western Pacific ................................................................................................................................. E. melanacme View in CoL (Fig. 53)

- Strongly granulose; grey mottled; Fiji Is .................................................................. E. feejeensis View in CoL (Fig. 57)

- Striate, granulose or rugose; white to grey; Western Australia ........................ E. australis View in CoL (part) (Fig. 50)

- Finely granulose; last whorl shouldered; white to grey; Philippines................. E. philippinensis View in CoL (Fig. 46)

8 Eroded parietal area ( Fig. 2D View FIGURE 2 ); strongly granulose ribs with single thread between; dirty white or mottled brown; northwestern Pacific ........................................................................................... E. radiata View in CoL ( Fig. 4 View FIGURE 4 )

- No eroded parietal area .............................................................................................................................. 9

9 Finely or strongly granulose; grey, orange, brown or black; Persian Gulf and Oman.. E. arabica View in CoL ( Fig. 8 View FIGURE 8 )

- 3 rows of small nodules; cream, yellow or orange; Red Sea ................................... E. marisrubri View in CoL ( Fig. 11 View FIGURE 11 )

10 Penial filament short, triangular (= half total penial length; Fig. 28A); 2 rows of nodules .................... 11

- Penial filament elongate (> half total penial length; Figs 22A View FIGURE 22 , 39A); 1–3 rows of nodules ................... 12

11 Japan............................................................................................................... E. cecillei View in CoL (Fig. 32; Table 1)

- Marquesas Is ......................................................................................... E. marquesensis View in CoL (Fig. 35; Table 1)

- Australia........................................................................................... E. austrotrochoides View in CoL (Fig. 30; Table 1)

- India to Southeast Asia ............................................................................. E. malaccana View in CoL (Fig. 27; Table 1)

12 1–2 rows of orange nodules; Western Australia ........................................ E. australis View in CoL (part) (Fig. 50E–G)

- 2 rows of whitish nodules; Indonesia...................................................... E. wallaceana View in CoL (Fig. 38; Table 1)

- 2 rows of whitish or grey nodules; Easter and Pitcairn Is ............................................. E. pascua View in CoL ( Fig. 21 View FIGURE 21 )

- 2–3 rows of whitish nodules; southern Arabia ........................................................ E. omanensis View in CoL ( Fig. 17 View FIGURE 17 )

- 3 rows of whitish nodules; East Africa and Madagascar.......................................... E. natalensis View in CoL ( Fig. 13 View FIGURE 13 )

- 3 rows of whitish nodules; Red Sea ......................................................................... E. subnodosa View in CoL ( Fig. 19 View FIGURE 19 )