Chthamalus ngankeeae Chan, Tsai & Tsao, 2024, sp. nov.
Creators: name: Chan, Benny K. K.
name: Tsai, Pei-Chen
name: Tsao, Yao-Feng
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Maxillopoda
Sessilia
Chthamalidae
Chthamalus
Chthamalus ngankeeae

description: Chthamalus ngankeeae sp. nov.
urn:lsid:zoobank.org:act: 9D9118DB-46BF-4CEF-8D75-DFFD2DA4010D
(Figs. 2–7)
Type material. Holotype: ASIZCR000458, intertidal rocks (high shores, at the same tidal zone as Tetraclita sp.) at Pantai Puteri, Lundu, Sarawak, Malaysia (1°43’29.3”N, 110°18’55.5”E, 9 Oct. 2009). Paratype: ASIZCR000459, Pantai Puteri, Lundu, Sarawak, Malaysia (1°42’57.8”N, 110°18’50.6”E, 28 July 2010). Paratype. ZRC 2023.0426. Pandan Beach, Lundu, Sarawak, Malaysia (1°45’55.9”N 109°51’48.8”E,10 Oct. 2009). Paratype: ASIZCR000460, Port Dickson, Negeri Sembilan, Malaysia (2°29’51”N 101°50’14”E, 16 Mar. 2009).
Other material examined (deposited in Benny K.K. Chan’s laboratory, Academia Sinica, Taiwan). Ch_mo_04, Ch_mo_112–117, Port Dickson, Negeri Sembilan, Malaysia (2°29’51”N 101°50’14”E, 16 Mar. 2009). Ch_mo_25– 52, Ch_mo_104–111, Pandan Beach, Lundu, Sarawak, Malaysia (1°45’55.9”N 109°51’48.8”E,10 Oct. 2009).
Diagnosis. Shell conical; 6 plates, external surfaces brown (brown morph) or white (white morph), surface with ridges; scutum triangular, tergal articular margin straight, prominent at basal 1/3 region, external surface of scutum with horizontal striations; tergum triangular, scutal articular margin straight, spur blunt. Tergal margin of scutum with articular ridge. Cirrus III slightly antenniform form, posterior ramus about 1.5 times longer than anterior ramus.
Description. Shell small, about 2–3 mm basal diameter, conical; 6 plates (rostrum, carina, paired lateral and paired rostral-lateral) (Fig. 2). Brown morph, shell light brown with obvious pale brown longitudinal ridges (Fig. 2A, B). White morph, shell white with white ridges (Fig. 2C–E). Opercular plates brown (brown morph) or white (white morph) (Fig. 2C–G). Scutum, triangular, occludent margin longest, followed by basal margin (about 0.8 times of occludent margin), tergal margin shortest (0.5 times of occludent margin). Tergal margin straight with articular ridge, perpendicular to basal margin, articular ridge prominent at basal region, extending 1/3 length of tergal articular margin. Occludent margin almost smooth. Scutal adductor scar oval, obvious. External surface of scutum with horizontal striations (Fig. 2C–G). Tergum approximate equilateral triangular, scutal articular margin straight, extending down to spur, spur blunt, wide, joining as curves to basal margin, basal margin concave, carina margin convex, several fine depressor crests at basal margin viewed at inner side, external surface striated (Fig. 2C–G).
Cirrus I without conical spines on dorsal surface, posterior ramus 6-segmented, anterior ramus 9-segmented (Fig. 3A), bidentate setae only observed in most distal segment of posterior ramus but not in anterior ramus (Fig. 3B, C). Both rami with serrulate setae in other segments, setae without basal guard (Fig. 3D). Cirrus II, posterior ramus 5-segmented, anterior ramus 7-segmented (Fig. 3E), distal segment with bidentate setae (Fig. 3F–H). Cirrus III anterior ramus 14-segmented, posterior ramus 23-segmented (Figs 4A), intermediate segments composed of 2 pairs of long and 2 pairs of short simple setae (Fig. 4B), distal segment with simple setae (Fig. 4C, D). Cirrus IV with posterior ramus and anterior rami 17-segmented (Fig. 4E) intermediate segments composed of 2 pairs of long and 2 pairs of short simple setae (Fig. 4F), distal segment with simple setae (Fig. 4G, H). Cirrus V with posterior ramus 15-segmented and anterior ramus 16-segmented (Fig. 5A), intermediate segments of both rami with 2 pairs of long and 2 pairs of short simple setae (Fig. 5B), distal segment with simple setae. Cirrus VI with anterior ramus and posterior ramus 19-segmented (Fig. 5C), intermediate segments of anterior and posterior rami composed of 2 pairs of long and 2 pairs of short simple setae (Fig. 5D, E), distal segment with simple setae (Fig. 5F). Penis long, slender, sparse setae along length, tip with dense bundle of setae (Fig. 5G, H).
Maxilla bilobed, serrulate setae on both lobes (Fig. 6D). Maxillule notched, 2 large setae above notch, 7 setae below notch at the middle portion of cutting edge, lower angle and margin with short spines (Fig. 6E–H). Mandible with 4 teeth, all teeth bidentate, lower margin (pecten) straight, about 1/4 of cutting margin, with 13 fine setae, inferior angle with pair of large setae (Fig. 7A–C). Mandibular palps rectangular, with dense setae at lower margin (Fig7D, E). Labrum slightly V-shaped, notch absent, dense setae at inner region of cutting margin, latter with numerous fine teeth (Fig. 7F–H).
Etymology. Chthamalus ngankeeae sp. nov. is named in honour of our friend, the late Dr. Ngankee Ng, who was a carcinologist in the National University of Singapore (NUS), for her friendship and her contributions to the taxonomy of varunid crabs. The present species was collected in 2009 and 2010 during collection trips in Sarawak, Malaysia. In 2010 (Fig. 8), the second author (P.-C.Tsai) of the present paper joined a collection trip with Dr. Ngan Kee Ng, Dr. Hsi-Te Shih and a Ph.D student from NUS to Sarawak, Sabah, and Labuan in western Borneo for further sampling, which left many happy memories (Fig. 8).
Distribution. Chthamalus ngankeeae sp. nov. is common on the middle and high shores of Sarawak (East Malaysia, western Borneo) and West Malaysia. It is most abundant above the oyster zone in the intertidal where coverage can reach about 90% (Fig. 1H). The brown morphs were collected in Pantai Puteri (Sarawak) and white morphs were collected in Pandan Beach (Sarawak) and Port Dickson. These two morphs were not present in the same site. Differences in environmental variables that lead to different degree of erosions can result in the appearance of these two morphs.
description: Published as part of Chan, Benny K. K., Tsai, Pei-Chen & Tsao, Yao-Feng, 2024, A new intertidal barnacle, Chthamalus ngankeeae sp. nov. (Balanomorpha: Chthamalidae) from the Malaysian Peninsula and western Borneo waters, pp. 26-43 in Zootaxa 5476 (1) on pages 30-31, DOI: 10.11646/zootaxa.5476.1.6, http://zenodo.org/record/12681484