Condyloderes multispinosus (McIntyre, 1962) Higgins, 1969

3.4. Condyloderes multispinosus (McIntyre, 1962) Higgins, 1969 View in CoL

( Figs. 13 View Fig and 14 View Fig ; Fig. S3 View Fig ; Tables 1, 2, 5; TableS2).

Centroderes multispinosus — McIntyre (1962).

Condyloderes multispinosus comb. nov. — Higgins (1969).

Condyloderes multispinosus — Higgins (1971, 1986, 1988), Moore (1973), Brown (1985), Huys & Coomans (1989), Nebelsick (1993), Adrianov & Malakhov (1994, 1999), Bamber (1997), Adrianov et al. (2002), Martorelli & Higgins (2004), SØrensen & Pardos (2008), SØrensen et al. (2010b), Neuhaus (2013), Neuhaus et al. (2019).

Condyloderes sp. 2 (Tyrrhenian Sea) — Dal Zotto & Todaro (2016).

3.4.1. Emended diagnosis

Neck placids with condyles in one lateral row in narrower placids and three lateral rows in broader placids; each narrower placid with one basal condyle; each broader placid with two condyles both in apical, intermediate, and basal lateral row; midventral placid with three apical and three basal condyles and two in intermediate lateral row; acicular spine middorsally on segments 1 ‾ 9 (on segment 10 in male only), midterminally on segment 11, laterodorsally on segment 10 in male only, lateroventrally on segments 1 ‾ 9, and laterodorsally on segment 10; cuspidate spine ventrolaterally on segments 2, 5, and 9 and lateral accessorily on segment 8, sometimes also middorsally on segments 5 and/or 7; type-6 sensory spot ventromedially on segments 1 (slightly more paraventrally), 2 ‾ 4 and 6 ‾ 9, lateroventrally on segment 10, sublaterally on segments 1 ‾ 3 and 5 ‾ 9, midlaterally on segments 1 and 2, laterodorsally on segments 1 ‾ 9, subdorsally on segment 10, and paradorsally on segments 1 (almost subdorsally), 2, and 4 ‾ 9; gland cell outlet ventromedially on segment 10; ventromedial appendage on segments 7 and 8 and area of micropapillae ventromedially on segment 9 in female only.

3.4.2. Examined material

One male ( USNM 1562541 ), two females ( USNM 1562542 , USNM 1562543 ), and one juvenile ( USNM 1562544 ), from off Banyuls-sur-Mer , Gulf of Lion . One female from off Rovinj , northern Adriatic Sea ( USNM 1562540 ). All specimens mounted for light microscopy ( Figs. 13 View Fig and 14 View Fig ; Fig. S3 View Fig ; Table 5). One male from off Trappeto , Gulf of Castellammare , Sicily, southern Tyrrhenian Sea , lost during observation; thus only few photographs were available for this specimen.

3.4.3. Brief description

The morphology of the specimens from the Mediterranean Sea agrees widely with that of the recently re-described specimens of C. multispinosus from the North Sea, so only differences are mentioned for the Mediterranean specimens here. For illustrations, data and morphological measurements see Figs. 13 View Fig , 14 View Fig , Fig. S3 View Fig , Tables 2 and 5, and Table S2.

Our findings report for the first time a female adult stage for C. multispinosus . The female exhibits a ventromedial appendage on each sternal plate of segments 7 and 8, which gives the impression of an extremely elongated sensory spot covered by numerous cuticular micropapillae ( Fig. 13E View Fig ). At its base, each structure shows a sclerotized cuticular duct penetrating the trunk cuticle. The duct seems to be surrounded by a cavity. The structures occur ventromedially on segment 7 and slightly more paraventrally on segment 8 ( Fig. 13E View Fig ; Tables 2 and 5; Table S2). Each sternal plate of segment 9 possesses a more or less rectangular area with rounded edges and prominent cuticular micropapillae ( Fig.13E View Fig ; Tables 2 and 5; Table S2). Pores and ducts penetrating the trunk cuticle do not seem to exist in this area. Alarge circular gonopore with a more sclerotized edge at its anterior margin and a less sclerotized edge at the posterior margin occurs on each sternal plate of segment 11 ( Fig. 13G View Fig ).

3.4.4. Sexual dimorphism

Males can be distinguished from females by the lack of the ventromedial appendage on each sternal plate of segments 7 and 8 versus its existence in females ( Fig. 13E View Fig ; Tables 2 and 5; Table S2), the lack of a more or less rectangular area with prominent cuticular micropapillae on each sternal plate of segment 9 versus its existence in females ( Fig.13E View Fig ; Tables 2 and 5; Table S2), the existence of a ventromedial gland cell outlet with a short sclerotized cuticular duct and an intra- and subcuticular cuticle-lined cavity on each sternal plate of segment 10 versus the lack of this outlet in females, the possession of a middorsal and a laterodorsal acicular spine on segment 10 thinner than on the remaining segments ( Fig. 14G View Fig ) versus the lack of these spines in females ( Fig. 14F View Fig ; Tables 2 and 5; Table S2), and by the lack of a large circular gonopore with a sclerotized edge at its anterior and posterior margin on each sternal plate of segment 11 versus its existence in females ( Fig. 13G View Fig ).

3.4.5. Variation

Out of the three specimens from the Gulf of Lion, one male (USNM 1562541) shows a middorsal cuspidate spine on segment 5 ( Fig. 14D View Fig ), whereas two females (USNM 1562542, USNM 1562543) reveal a middorsal cuspidate spine on segments 5 and 7 ( Fig. 14E View Fig ). The female from the northern Adriatic Sea (USNM 1562540) lacks any middorsal cuspidate spine.

3.4.6. Juvenile stage

One small specimen (trunk length = 149 M m) possesses a very thin cuticle, has segments 10 and 11 still fused, lacks a free flap but shows a series of postmarginal spicula with a stronger base, and reveals papilla-like sensory spots elevated above the surface of the cuticle ( Fig. S3A—D View Fig ). Based on these observations, this specimen is regarded as a juvenile stage. Placids with condyles exist but are difficult to separate from each other. The trunk is composed of segments 1—9 separated from each other and from segments 10 + 11 which are still fused ( Fig. S3B View Fig ). Segment 1 reveals a single cuticular plate, whereas segments 2 ‾ 11 probably possess one tergal and one sternal plate ( Fig. S3A View Fig ). Short cuticular hairs with a stronger base cover all segments except ventromedially and midlaterally, where the dorsoventral muscles originate ( Figs. S3A and B View Fig ). A type-3 sensory spot occurs ventrolaterally and subdorsally on segment 11 ( Fig. S3B View Fig ). Type-6 sensory spots appear at least ventromedially on segments 2, 5, and 9, sublaterally on segments 1, 3, 6, 7, and 9, and paradorsally on segments 1 (almost subdorsally), 4, and 6 ‾ 9 ( Fig. S3A—D View Fig ). Acicular spines are found lateroventrally and middorsally on segments 1 ‾ 10 as well as in a lateral accessory position and midterminally on segment 11 ( Fig. S3A—D View Fig ). Cuspidate spines are located ventrolaterally on segments 2, 5, and 9, in a lateralaccessory position on segments 4 and 8, and middorsally on segment 5 ( Fig. S3A—D View Fig ).

3.4.7. Comparison with previous descriptions

The species was originally described as Centroderes multispinosus by McIntyre (1962) and later placed in a new genus and combined as Condyloderes multispinosus (McIntyre, 1962) by Higgins (1969). Most recently, Neuhaus et al. (2019) re-described the male holotype and three additional males from the North Sea. The specimens from the Mediterranean Sea differ from the specimens from the North Sea in the possession of a type-6 sensory spot ventromedially on segments 5 and 11 versus the lack of these spots in the specimens from the North Sea and in the existence of a middorsal cuspidate spine on segments 5 and/or 7 at least in some specimens versus their lack in the northern population. The juvenile specimen from the Mediterranean Sea possesses a cuspidate spine in a lateral accessory position on segment 4, which is missing in any adult specimen from the North Sea and from the Mediterranean Sea. We regard the above mentioned differences as variation within one and the same species. It should be kept in mind that few specimens of this species are known both from the North Sea and from the Mediterranean Sea ( Table S2). In any case, this study expands the distribution record of C. multispinosus considerably from the North Sea to the Mediterranean Sea suggesting that the species should also occur in the northeastern Atlantic Ocean.

3.4.8. Co-occurrence of C. multispinosus and C. agnetis sp. nov.

Asingle male of C. multispinosus was collected together with C. agnetis sp. nov. at a station off Trappeto, Gulf of Castellammare, Sicily, southern Tyrrhenian Sea (Table 1). The two species also occurred in almost the same location off Rovinj, northern Adriatic Sea, but were collected in different years (Table 1).