Periclimenes pholeter Holthuis, 1973

Grave, De, 2011, Further records of the anchialine shrimp, Periclimenes pholeter Holthuis, 1973 (Crustacea, Decapoda, Palaemonidae), Zootaxa 2903, pp. 64-68 : 64-67

Periclimenes pholeter Holthuis, 1973

( Figs. 1–2 )

Periclimenes pholeter Holthuis, 1973: 30 , Figs. 10–11; Plate 1.— Bruce, 1992: 74; Figs. 22–23.— Bruce, 2011: 119, Fig. 1 .

Material examined. i) 4 males (pocl 3.00–4.60), 6 females (pocl 1.80–5.05), OUMNH.ZC. 2010-12 -0032; Sombano lake, Kaledupa Island, Tukangbesi Archipelago, Sulawesi, Indonesia, leg. S. De Grave, 09.vii.2000.

ii) 2 females (pocl 10.60, 12.05) OUMNH.ZC. 2010-13 -0009, Keawaiki, Manukā Watershed, Ka‘ū District, Hawai‘i, leg T. Sakihara, 12.iv.2010

iii) 1 male (pocl 4.50), 1 female (pocl 5.50); OUMNH.ZC. 2010-20 -0014; Easo (II) cave, Lifou, Loyalty Islands, leg. G. Boxshall & D. Jaume, 18.x.2000.

Taxonomic remarks. Although the material corresponds closely to the type description by Holthuis (1973) and the description of additional material by Bruce (1992), some variation was noted in the present material.

The Sulawesi ( Fig. 1 A–D) and Lifou ( Fig. 1 E) material is very similar to each other, with all specimens harbouring an epigastric tooth, with the number of dorsal teeth on the rostrum varying from 10 to 12, none however have any ventral rostral teeth. In most specimens a double row of setae was present along the ventral margin of the rostrum. The small tubercle posterior to the epigastric tooth is absent in approximately half of the material examined. The rostrum as a whole is distinctly shorter than the material from the Red Sea ( Bruce, 1992), generally not exceeding the distal margin of the second segment of the antennular peduncle. Further differences are that the distal, dorsal margin of the rostrum is generally provided with teeth in the current material, and not unarmed as in some of the deep water material in Bruce (1992) and the type material, both of which had the distal third of the dorsal margin devoid of teeth ( Holthuis, 1973; Bruce, 1992, 2011). The material from Lifou and Sulawesi appears very similar to both the specimens from Fiji discussed in Bruce (1992, Fig. 23C), as well as the juvenile deep-water specimens. ( Bruce, 1992, Fig. 23A–B).

The two specimens from Hawai‘i ( Fig. 1 F–H) are morphologically closer to the anchialine material in Holthuis (1973) and the deep water specimens in Bruce (1992). Only one specimen harbours an epigastric tooth, although both specimens have the characteristic posterior tubercle. Dorsal rostral dentition varies between 10 and 11, whilst both specimens also harbour 2 ventral teeth, no double row of setae was present along the ventral margin. Additionally, the rostrum of the undamaged specimen reaches to the end of the third segment of the antennular peduncle, whilst the distal third of the dorsal margin is unarmed.

The Sulawesi and Lifou specimens are smaller than those from Hawai‘i, with the post-orbital carapace lengths of males from Lifou and Sulawesi ranging from 3.0 to 4.6 mm and 1.8–5.5 in females, smaller than the material from Fiji, reported in Bruce (1992). The two specimens from Hawai‘i have a pocl of 10.6 and 12.05 respectively, a more similar size to the deep water specimens reported upon by Bruce (1992). The type material ranged in size from 8.5 to 9.0 in males, and 9.0– 9.5 in females ( Holthuis, 1973).

Although Bruce (1992) very tentatively implied that the material from Fiji may ultimately warrant subspecific status, pending the availability of further material, the observed variation in the current material appears more indicate of a somewhat morphologically, variable species. Such variability is more consistent with a species occurring in very disjunct population across a very large area, over which there may only be very limited recent gene flow.

Habitat. Specimens from Lifou were collected in a cenote type cave, with a collapsed roof, approximately 30–40 m in diameter, and 30 metres deep. The water filled cave bellows this, drops rapidly in depth and is at least 56 m deep. Samples were obtained by baited trap in the upper parts of the water column. Other species of shrimp caught in the traps were Antecaridina lauensis ( Edmondson, 1935) and Metabetaeus minutus .

The specimens from Sulawesi were obtained in Sombano Lake on Kaledupa Island in south-eastern Sulawesi. Sombano Lake is a small anchialine lake, situated about 100 m inland but with clear tidal influence. The lake is about 50 m long and in places 5–10 m wide, approximately 1.5–2.0 m deep on high tide. Sargassum sp. was very common in the well-lit parts of the lake, with Parhippolyte uveae Borradaile, 1900 also being a conspicuous part of the fauna, which otherwise consisted of an unidentified chiton and several unidentified amphipod species.

The two specimens from Hawai‘i were collected from the Manukā watershed on the southwest coast of the Island of Hawai‘i. Collection sites were located on unencumbered state land near the coastal border of the Manukā Natural Area Reserve, which was established in 1983 by the State of Hawai‘i. Anchialine habitats within this remote area are characterized by shallow complexes of pools (average depth = <0.5 ± 0.30 m), interspersed throughout barren basaltic lava fields in a relatively arid environment. Notably, these pools are uncharacteristic of Hawaiian anchialine habitats with respect to its lack of periphyton, which is typically found in anchialine pools in Hawai‘i ( Bailey-Brock & Brock, 1993). Furthermore, the anchialine habitats in Manukā exhibit particularly high saline conditions that are suggested to provide favourable habitat for rarer anchialine species ( Maciolek, 1983; Brock, 2004). Such is evident by the occurrence of rare anchialine decapods in these pools making the anchialine habitats in Manukā some of the most unique and biodiverse in Hawai‘i ( Chan, 1995; Brock, 2004).

Figures

FIGURE 1. Periclimenes pholeter Holthuis, 1973. Sulawesi, A, carapace (female, pocl 5.0); B, rostrum (male, pocl 4.2), C, rostrum (female, 5.0); D, second pereiopod, chela (female, pocl 5.0). Lifou, E, anterior carapace and appendages (female, pocl 5.4). Hawai‘i, F, anterior carapace and appendages (female, pocl 12.05); G, rostrum (female, pocl 10.6); H, second pereiopod, chela (female, pocl 10.6). Scale bar indicates 0.5 mm (D), 1 mm (A – C, E, H) or 2 mm (F – G).

FIGURE 2. Periclimenes pholeter Holthuis, 1973. Manukā Watershed, Ka‘ū District, Hawai‘i, female (pocl 10.6).