Endeis biseriata Stock, 1968

B, Rudá Amorim Lucena, Fatemi, Yaser & B, Martin Lindsey Christoffersen, 2018, Checklist of sea spiders (Arthropoda: Pycnogonida) from the Persian Gulf and the Gulf of Oman with new record of Endeis biseriata (Böhm, 1879) for the region, Turkish Journal of Zoology 42 (6), pp. 709-714 : 710-713

Endeis biseriata Stock, 1968 ( Figures 2 and 3 )

- Phoxichilus meridionalis Loman, 1908

Material examined: ( ZUHPY 01) 1 female, 25°21′07.2.5″N, 60°36′04.1″E, Chabahar Bay , Iran, intertidal on Padina sp. , col. Yasser Fatemi, February 2017 .

Diagnosis: Elongated animal. Lateral processes separated by 2× their own diameter; with a dorsal small tubercle (two in the first lateral process). Proboscis measuring 3/4 of body length; with the proximal third narrower than the remainder of the proboscis. Ocular tubercle pointed; smaller than the abdomen. Legs elongated. Coxa 1 short, with a dorsal spiniform tubercle. Coxa 2 elongated, almost the same size as coxae 1 and 3 together. Femur elongated, with few long setae; some legs with a constriction in the first half; distal region with two lateral tubercles and an elongated dorsal spur. Tibia 1 shorter than femur, with a dorsodistal tubercle having an apical seta. Tibia 2 longer than femur, with small setae. Propodus elongated and well curved; with three large heel spines; sola with 6 small spines. Main claw little more than half the length of the propodus. Auxiliaries 1/2 of main claw.

Measurements (in mm): Length of trunk: 3; length of proboscis: 1.7; length of ocular tubercle: 0.32; length of abdomen: 0.57; length of article of 3rd leg – coxa 1: 0.35; coxa 2: 1; coxa 3: 0.52; femur: 2.3; tibia 1: 2; tibia 2: 2.3; tarsus: 0.12; propodus: 0.86; main claw: 0.4; auxiliary claw: 0.2.

Distribution: Seget, West New Guinea (type locality), India, Indonesia ( Stock, 1968); Philippines ( Child, 1988); Australia ( Child, 1990; Arango, 2001, 2003); Papua New Guinea ( Child, 1996); USA (Hawaii) ( Stock, 1968); Brazil ( Stock, 1979, 1992b); Antigua and Barbuda? ( Stock, 1992b); Red Sea ( Stock, 1970); Madagascar ( Stock, 1974) ( Figure 3 ).

LUCENA et al. / Turk J Zool

Depth: 0 to 46 m.

Remarks: Endeis biseriata is considered to probably represent a native Indo-Pacific species. However, it has a wide world distribution, being probably a pantropical species ( Child, 1996; Carlton and Eldredge, 2009). According to Stock (1968) the main characters that distinguish it from its congeners are the number of pores of the gland in the femurs of the males and the presence of a spur in the distal region of the femur, both possibly unique in the genus. Additionally, Child (1996) pointed out that the absence of a lateral intestinal cecum and elongated spines can be used as diagnostic characters.

LUCENA et al. / Turk J Zool

Our specimen agrees with the description made by Stock (1968) (excluding male characteristics). The only variations were the length of the spur in the femur, which is slightly larger than that described for females, and smaller than that of males, as well as a small tubercle with an apical setae elongated at the dorsodistal margin of tibia 1. A slight constriction was observed in the proximal half of the femur of some legs.

According to Child (1990) variations occur in the size of femur spurs in individuals of E. biseriata from different parts of the world. While the Indo-Pacific populations generally have the pattern described by Stock (1968) (long in males and short in females), females recorded in Australia have more elongated spurs ( Child, 1990), while Brazilian specimens have the spur shorter than originally described ( Stock, 1979, 1992b). Although we analyzed a female specimen, it presents a more elongated spur, slightly smaller than that described by Stock (1968) for males and larger than that described for females.

Until 2018 about 33,400 species of animals were recorded from Iranian waters of the Persian Gulf and the Gulf of Oman ( Maghsoudlou et al., 2017). However, many surveys are less than comprehensive, so we may anticipate that many more species will be found in the Gulf of Oman.

Based on the presence of high variety of marine habitats in the gulf, the high diversity of marine algae, and the considerable depths of the gulf and areas facing the open ocean ( Reynolds, 1993; Gharanjik and Rohani-Ghadikolaei, 2010; Sohrabipour and Rabiei, 2007), we may conclude that a moderate diversity of pycnogonids can be expected for the gulf. Currently, 16 pycnogonid species were recorded for the Gulf of Oman ( Stock, 1992a), and eight species have been recorded from adjacent waters (Persian Gulf) by Stock (1968) and Child (2002) (Table).

Although the western region of the Arabian Sea is considered a center of endemism, there have been few studies on pycnogonids: those of Calman (1923 – India), Stock (1968 – Persian Gulf), Moazzam (1987 – Pakistan), Stock (1992a – Oman), Child (2002 – Saudi Arabia), Bartolino and Krapp (2007 – Socotra), and Gul and Ghani (2012 – Pakistan). These contributions comprise a total of 36 species recorded for the Arabian Sea. Of these, 16 were recorded for the Gulf of Oman, all restricted to Oman (see Stock, 1992a).

For Iranian waters, there is no record of Pycnogonida up to the present time. This is also the first record of the genus Endeis and of the species E. biseriata for the Gulf of Oman. Among species widely recorded in the world, only two have been recorded near the Gulf of Oman: E. meridionalis and E. mollis (see Gul and Ghani, 2012). These three species can be separated mainly by the presence of a spur in the distal femur of all legs of E. biseriata (absent in other species), elongate and strongly curved in E. biseriata , elongated and more erect in E. mollis , and more robust and short in E. meridionalis . In addition, the amount of spines in the sole of the propodus can aid in identification, since E. mollis has 8 to 10 spines, E. biseriata 6 to 7, and E. meridionalis 5.

The presence of a spur in the distal region of the femur in E. meridionalis from Pakistan was mentioned by Gul and Ghani (2012). It is possible that it is actually E. biseriata and not E. meridionalis . However, only a detailed morphological analysis of the specimen can confirm our suspicion.

Figures

Figure 2. Endeis biseriata, female: A- dorsal view; B- lateral view; C- frontal view; D- propodus; E- third leg; F- coxae.

Figure 3. Distribution of Endeis biseriata around the world. Blue circles: previous records; Red circle: present record.