IUPAC systematic name of Carminic Acid Every IUPAC Systematic name I have come across, I have understood up until now. This is Carminic Acid ($\ce{C22H20O13}$):

(source: chemspider.com)
This is the IUPAC Systematic Name for Carminic Acid:
(1S)-1,5-Anhydro-1-(7-carboxy-1,3,4,6-tetrahydroxy-8-methyl-9,10-dioxo-9,10-dihydro-2-anthracenyl)-D-glucitol
I have 3 main questions:

I do not understand the numbering system inside the brackets. The numbering system implies that the numbers assigned to the carbon atoms is the following:


I would have thought the numbers assigned to the carbon atoms would be the following:

Why is the numbering system the way it is? (Why does the numbering system not go around the molecule, in a normal cycle, counting off each carbon?, Why is the number 10 carbon opposite the number 9 carbon?, Why are 4 carbons [circled in the picture below] left out in the numbering system?)



I also do not understand why Carbons 9 and 10 in the anthracene group are referred to as '9,10-dioxo-9,10-dihydro'. Surely, they only need to be referred to as '9,10-dioxo'? And what is a '-hydro' group?



Doesn't '1,5-Anhydro...-D-Glucitol' imply the following: Hexan-2,3,4,6-tetrahydroxy-1-yl, a chain, and NOT a ring structure of: Oxan-3,4,5-trihydroxy-6-hydroxymethyl-2-yl, considering D-Glucitol (shown below). Also, as well as '1,5-Anhydro...-D-Glucitol' not accounting for the ring structure of that section of the molecule, it also doesn't account for the Oxygen.
According to the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), the preferred name (PIN) for the parent ring component consisting of three benzene rings fused in a linear manner is the retained name anthracene.

Subsection P-25.1.1, Table 2.7, Entry (11) shows that anthracene has a special numbering:



According to Subsection P-14.4 (a), this fixed numbering must be used in PINs and in general nomenclature.

The prefixes ‘hydro’ and ‘dehydro’ are used to indicate addition and subtraction, respectively, of hydrogen atoms (see Subsection P-31.2.1).  Hence, the PIN for the ring component of the structure given in the question is 9,10-dihydroanthracene:



The corresponding monovalent substituent groups derived from such ring systems by the removal of one hydrogen atom are named by replacing the final ‘e’ of the name of the hydrocarbon by ‘yl’ (see Section P-29). Thus, the name for the substituent group derived from 9,10-dihydroanthracene is (9,10-dihydroanthracen-2-yl):



(Note that locants are placed immediately before that part of the name to which they relate (see Subsection P-14.3.2); i.e. ‘…anthracen-2-yl’. Thus, the name ‘…-2-anthracenyl’ given in the question is not correct.)

The substitutive prefixes for the remaining groups are
‘methyl’ $(\ce{-CH3})$,
‘hydroxy’ $(\ce{-OH})$,
‘oxo’ $(\ce{=O})$, and
‘carboxy’ $(\ce{-COOH})$.

The name for the complete substituent group is (7-carboxy-1,3,4,6-tetrahydroxy-8-methyl-9,10-dioxo-9,10-dihydroanthracen-2-yl):





The bases for carbohydrate names are the structures of the parent monosaccharides in their acyclic form (see Subsection P-102.2).
Alditols are named by changing the ending ‘ose’ in the name of the corresponding aldose into ‘itol’ (see Subsection P-102.5.6.5):



The prefix ‘anhydro’ expresses the corresponding intramolecular ether, which is formally obtained by elimination of water from two hydroxy groups of a single molecule of a monosaccharide or monosaccharide derivative (hence the structure is commonly called an intramolecular anhydride). The prefix ‘anhydro’ is preceded by a pair of locants identifying the two hydroxy groups (see Subsection P-102.5.6.7.1).